linux/const.h: Add _BITUL() and _BITULL()

Add macros for single bit definitions of a specific type.  These are
similar to the BIT() macro that already exists, but with a few
exceptions:

1. The namespace is such that they can be used in uapi definitions.
2. The type is set with the _AC() macro to allow it to be used in
   assembly.
3. The type is explicitly specified to be UL or ULL.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-nbca8p7cg6jyjoit7klh3o91@git.kernel.org