This is a simple shell module that allows arbitrary boards with flash
driver support to explore the flash device.
- Reading, erasing, and writing by device offsets are supported in all
cases.
- If the flash page layout is available, it can be printed, and I/O
can also be done to a specified page as well.
One known issue is that writing to flash on targets that require
doubleword-sized writes (e.g STM32L4) will fail since the number of
arguments required exceeds ARGC_MAX in shell.c. Addressing that is
left to future work.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>