[ARM] pxa: introduce sysdev for IRQ register saving/restoring

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-pxa/generic.h b/arch/arm/mach-pxa/generic.h
index b30f240..367b679 100644
--- a/arch/arm/mach-pxa/generic.h
+++ b/arch/arm/mach-pxa/generic.h
@@ -52,3 +52,5 @@
 #define pxa3xx_get_clk_frequency_khz(x)		(0)
 #define pxa3xx_get_memclk_frequency_10khz()	(0)
 #endif
+
+extern struct sysdev_class pxa_irq_sysclass;