[PATCH] x86_64: avoid wasting IRQs patch update

The patch adds boundary check for the MAX_GSI_NUM.  Same as the update for
i386, the patch addresses a problem with ACPI SCI IRQ.  The patch corrects
the code such that SCI IRQ is skipped and duplicate entry is avoided.  The
VIA chipset uses 4-bit IRQ register for internal interrupt routing, and
therefore cannot handle IRQ numbers assigned to its devices.  The patch
corrects this problem by allowing PCI IRQs below 16.

Signed-off-by: Natalie Protasevich <Natalie.Protasevich@unisys.com>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>