We have many variants of the same bitops.h file. Consistently
use the same file for all architectures which completely use
the generic bitops versions.

Some architectures had static inline versions of functions
identically to the generic versions, these are removed and
the generic versions are used directly now.

Also several architectures depend on the generic find_*_bit
functions but didn't have the GENERIC_FIND_NEXT_BIT Kconfig
option selected. This is added where needed.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>