mshv: Add data for printing stats page counters

mshv: Add data for printing stats page counters

Introduce mshv_debugfs_counters.c, containing static data
corresponding to HV_*_COUNTER enums in the hypervisor source.
Defining the enum members as an array instead makes more sense,
since it will be iterated over to print counter information to
debugfs.

Include hypervisor, logical processor, partition, and virtual
processor counters.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>