x86, dmar: use atomic allocations for QI and Intr-remapping init

Impact: invalid use of GFP_KERNEL in interrupt context

Queued invalidation and interrupt-remapping will get initialized with
interrupts disabled (while enabling interrupt-remapping). So use
GFP_ATOMIC instead of GFP_KERNEL for memory alloacations.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>