sh: mach-x3proto: Migrate to linear irq domain.

In the interest of getting off of the create_irq() API we can get all of
the functionality we're interested in through a linear IRQ domain. Fairly
straightforward conversion utilizing a single linear domain.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/boards/Kconfig

@@ -292,6 +292,7 @@ config SH_X3PROTO
 	bool "SH-X3 Prototype board"
 	depends on CPU_SUBTYPE_SHX3
 	select NO_IOPORT if !PCI
+	select IRQ_DOMAIN
 
 config SH_MAGIC_PANEL_R2
 	bool "Magic Panel R2"