[media] m5mols: Add missing #include <linux/sizes.h>

Include <linux/sizes.h> header that is missing after commit ab7ef224


"[media] m5mols: Implement .get_frame_desc subdev callback".
It prevents possible build errors due to undefined SZ_1M.

This header is currently included only when m5mols is compiled
on arm; if build on other archs, the compilation will break.

Reported-by: Jan Hoogenraad <jan-conceptronic@hoogenraad.net>
Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>