arm64: allow vmalloc regions to be set with set_memory_*

arm64: allow vmalloc regions to be set with set_memory_*

The range of set_memory_* is currently restricted to the module address
range because of difficulties in breaking down larger block sizes.
vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the
function ranges and add a comment explaining why the range is restricted
the way it is.

Suggested-by: Laura Abbott <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Will Deacon <[email protected]>