fs: ext4: Fix building ext4 in SPL if write is enabled

If EXT4_WRITE is enabled, write capabilities will be compiled into SPL, but
not CRC16. Add an option to enable CRC16 to avoid linker errors.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
3 files changed