[ARM] 4136/1: Allow PXA2xx's clock source to be used

Commit c80204e5d6 apparently missed this.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -280,6 +280,7 @@ config ARCH_PXA
 	bool "PXA2xx-based"
 	depends on MMU
 	select ARCH_MTD_XIP
+	select GENERIC_TIME
 	help
 	  Support for Intel's PXA2XX processor line.