List field desciptions if field is matching

[will-v-pi]

With otp list, show field descriptions if a field is matched, or if the -f flag is set:

$ picotool otp list crit1
ROW 0x0040: OTP_DATA_CRIT1
        "Page 1 critical boot flags (RBIT-8)"
    field GLITCH_DETECTOR_SENS (bits 5-6)
    field GLITCH_DETECTOR_ENABLE (bit 4)
    field BOOT_ARCH (bit 3)
    field DEBUG_DISABLE (bit 2)
    field SECURE_DEBUG_DISABLE (bit 1)
    field SECURE_BOOT_ENABLE (bit 0)

$ picotool otp list crit1 -f
ROW 0x0040: OTP_DATA_CRIT1
        "Page 1 critical boot flags (RBIT-8)"
    field GLITCH_DETECTOR_SENS (bits 5-6)
        "Increase the sensitivity of the glitch detectors from their default."
    field GLITCH_DETECTOR_ENABLE (bit 4)
        "Arm the glitch detectors to reset the system if an abnormal clock/power event is observed."
    field BOOT_ARCH (bit 3)
        "Set the default boot architecture, 0=ARM 1=RISC-V. Ignored if ARM_DISABLE, RISCV_DISABLE or SECURE_BOOT_ENABLE is set."
    field DEBUG_DISABLE (bit 2)
        "Disable all debug access"
    field SECURE_DEBUG_DISABLE (bit 1)
        "Disable Secure debug access"
    field SECURE_BOOT_ENABLE (bit 0)
        "Enable boot signature enforcement, and permanently disable the RISC-V cores."

$ picotool otp list crit1.boot_arch
ROW 0x0040: OTP_DATA_CRIT1
        "Page 1 critical boot flags (RBIT-8)"
    field BOOT_ARCH (bit 3)
        "Set the default boot architecture, 0=ARM 1=RISC-V. Ignored if ARM_DISABLE, RISCV_DISABLE or SECURE_BOOT_ENABLE is set."

Fixes #134

[lurch]

I wonder if the "row description" should be less indented than the "field description", to make them more visually distinct? e.g.

$ picotool otp list crit1 -f
ROW 0x0040: OTP_DATA_CRIT1
    "Page 1 critical boot flags (RBIT-8)"
    field GLITCH_DETECTOR_SENS (bits 5-6)
        "Increase the sensitivity of the glitch detectors from their default."
    field GLITCH_DETECTOR_ENABLE (bit 4)
        "Arm the glitch detectors to reset the system if an abnormal clock/power event is observed."

[will-v-pi]

I wonder if the "row description" should be less indented than the "field description", to make them more visually distinct?

It might be better to just add a newline instead, so it still matches the otp get command?

$ picotool otp get crit1
ROW 0x0040: OTP_DATA_CRIT1
        "Page 1 critical boot flags (RBIT-8)"

    VALUE 0x000000

    field GLITCH_DETECTOR_SENS (bits 5-6) = 0
        "Increase the sensitivity of the glitch detectors from their default."
    field GLITCH_DETECTOR_ENABLE (bit 4) = 0
        "Arm the glitch detectors to reset the system if an abnormal clock/power event is observed."
    field BOOT_ARCH (bit 3) = 0
        "Set the default boot architecture, 0=ARM 1=RISC-V. Ignored if ARM_DISABLE, RISCV_DISABLE or SECURE_BOOT_ENABLE is set."
    field DEBUG_DISABLE (bit 2) = 0
        "Disable all debug access"
    field SECURE_DEBUG_DISABLE (bit 1) = 0
        "Disable Secure debug access"
    field SECURE_BOOT_ENABLE (bit 0) = 0
        "Enable boot signature enforcement, and permanently disable the RISC-V cores."