x86/irq: Standardize on CONFIG_SPARSE_IRQ=y

Sparseirq got introduced in v2.6.28 and Thomas did a huge cleanup
around v2.6.38 that eliminated basically all disadvantages
of it.

So we can remove non-sparseirq support now and simplify
our IRQ degrees of freedom a bit.

Suggested-and-acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/4E95E21D.6090200@oracle.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6a47bb2..fcd34c3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -64,6 +64,7 @@
 	select HAVE_TEXT_POKE_SMP
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_SPARSE_IRQ
+	select SPARSE_IRQ
 	select GENERIC_FIND_FIRST_BIT
 	select GENERIC_IRQ_PROBE
 	select GENERIC_PENDING_IRQ if SMP