ARM: pxa: add rtc dummy clock

sa1100-rtc driver could be shared among sa1100/pxa/mmp series silicon.
Since clk is used in mmp series silicon, add dummy clock support in
pxa also.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
diff --git a/arch/arm/mach-pxa/pxa3xx.c b/arch/arm/mach-pxa/pxa3xx.c
index 4f402afa..8819348 100644
--- a/arch/arm/mach-pxa/pxa3xx.c
+++ b/arch/arm/mach-pxa/pxa3xx.c
@@ -89,6 +89,7 @@
 	INIT_CLKREG(&clk_pxa3xx_mmc2, "pxa2xx-mci.1", NULL),
 	INIT_CLKREG(&clk_pxa3xx_smemc, "pxa2xx-pcmcia", NULL),
 	INIT_CLKREG(&clk_pxa3xx_gpio, "pxa-gpio", NULL),
+	INIT_CLKREG(&clk_dummy, "sa1100-rtc", NULL),
 };
 
 #ifdef CONFIG_PM