sgi-xp: add usage of GRU driver by xpc_remote_memcpy()

Add UV support to xpc_remote_memcpy(), which involves interfacing to the
GRU driver.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>