wait_bit: add 8/16/32 BE/LE versions of wait_for_bit

Add 8/16/32 bits and BE/LE versions of wait_for_bit.
This is needed for reading registers that are not aligned to 32 bits, and for
Big Endian platforms.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>