Include header linux/bitops.h, directly use its BIT() macro and remove
the self defined macros.

Committer notes:

Use BIT_ULL() instead of BIT to build on 32-bit arches as mentioned in
review by Andre Przywara <andre.przywara@arm.com>. I noticed the build
failure when crossbuilding to arm32 from x86_64.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20201111071149.815-2-leo.yan@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>