sh: Tie sparseirq in to Kconfig.

Now that the dependent patches are merged, we are ready to enable
sparseirq support. This simply adds the Kconfig option, and then converts
from the _cpu to the _node allocation routines to follow the upstream
sparseirq API changes.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index b5629cd..586cd04 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -678,6 +678,18 @@
 	  LLSC, this should be more efficient than the other alternative of
 	  disabling interrupts around the atomic sequence.
 
+config SPARSE_IRQ
+	bool "Support sparse irq numbering"
+	depends on EXPERIMENTAL
+	help
+	  This enables support for sparse irqs. This is useful in general
+	  as most CPUs have a fairly sparse array of IRQ vectors, which
+	  the irq_desc then maps directly on to. Systems with a high
+	  number of off-chip IRQs will want to treat this as
+	  experimental until they have been independently verified.
+
+	  If you don't know what to do here, say N.
+
 endmenu
 
 menu "Boot options"