bitops: Introduce a more generic BITMASK macro

GENMASK is used to create a contiguous bitmask([hi:lo]). It is
implemented twice in current kernel. One is in EDAC driver, the other
is in SiS/XGI FB driver. Move it to a more generic place for other
usage.

Change-Id: Ia8d2d7c9f6e143fee7338f5bb991658fffef52ec
Signed-off-by: Chen, Gong <gong.chen@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
[dramasub@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>
Git-commit: 10ef6b0dffe404bcc54e94cb2ca1a5b18445a66b
Git-repo: https://github.com/torvalds/linux.git