This patch, from Venkatesh Pallipadi, changes x86 IO-APICs to use fixed
interrupt delivery instead of lowest priority to support larger number
of CPUs.  Only bigsmp is affected by this cleanup. 

From: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>