x86: SGI UV: Fix IPI macros

The UV BIOS has changed the way interrupt remapping is being done.
This affects the id used for sending IPIs. The upper id bits no
longer need to be masked off.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Cc: <stable@kernel.org>
LKML-Reference: <20090909154104.GA25083@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>