[ARM] 5212/1: pxa: fix build error when CPU_PXA310 is not defined

Fix
arch/arm/mach-pxa/pxa300.c:94: error: 'CKEN_MMC3' undeclared here (not in a function)
when building for PXA300.
Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/pxa300.c

@@ -90,7 +90,9 @@ static struct clk common_clks[] = {
 };
 
 static struct clk pxa310_clks[] = {
+#ifdef CONFIG_CPU_PXA310
 	PXA3xx_CKEN("MMCCLK", MMC3, 19500000, 0, &pxa3xx_device_mci3.dev),
+#endif
 };
 
 static int __init pxa300_init(void)