x86: pre init pirq_entries[]

Impact: cleanup

set default value early - this allows the removal of a number
of dynamic initialization codepaths, and an #ifdef.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>