x86: Add UV bios call infrastructure v4

Add the EFI callback function and associated wrapper code.
Initialize SAL system table entry info at boot time.

Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Paul Jackson <pj@sgi.com>
Acked-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>