GitLab

A board can now define the following to fully customise the extended block
device interface provided by the storage sub-system:
- MICROPY_HW_BDEV_BLOCKSIZE_EXT
- MICROPY_HW_BDEV_READBLOCKS_EXT
- MICROPY_HW_BDEV_WRITEBLOCKS_EXT
- MICROPY_HW_BDEV_ERASEBLOCKS_EXT
Signed-off-by: Damien George <damien@micropython.org>