x86/resctrl: Add arch_has_{sparse,empty}_bitmaps to explain CAT differences

Intel CPUs expect the cache bitmap provided by user-space to have on
a single span of 1s, whereas AMD can support bitmaps like 0xf00f.
Arm's MPAM support also allows sparse bitmaps.

Similarly, Intel CPUs check at least one bit set, whereas AMD CPUs
are quite happy with an empty bitmap. Arm's MPAM allows an empty
bitmap.

To move resctrl out to /fs/ we need to explain platform differences
like this. Add two resource properties arch_has_{empty,sparse}_bitmaps.
Test these around the relevant parts of cbm_validate().

Merging the validate calls causes AMD to gain the min_cbm_bits test
needed for Haswell, but as it always sets this value to 1, it will
never match.

CC: Babu Moger <Babu.Moger@amd.com>
CC: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: James Morse <james.morse@arm.com>