Getting rid of the literal number has been something I've been
hoping to see happen for perhaps over 10 years, along with
doing away with some unnecessary refusal of operations. The
other two changes are "collateral damage" from doing that
change.

1: gnttab: adjust pin count overflow checks
2: gnttab: consolidate pin-to-status syncing
3: Arm: don't hard-code grant table limits in create_domUs()

Jan