ARM: versatile: Make plat-versatile clock optional

... in preparation for common clock coming for Integrator
and Versatile Express.

Based on Linus Walleij's "ARM: integrator: convert to common
clock" patch.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a91009c..17beb66 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -260,6 +260,7 @@
 	select ICST
 	select GENERIC_CLOCKEVENTS
 	select PLAT_VERSATILE
+	select PLAT_VERSATILE_CLOCK
 	select PLAT_VERSATILE_FPGA_IRQ
 	select NEED_MACH_IO_H
 	select NEED_MACH_MEMORY_H
@@ -277,6 +278,7 @@
 	select GENERIC_CLOCKEVENTS
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select PLAT_VERSATILE
+	select PLAT_VERSATILE_CLOCK
 	select PLAT_VERSATILE_CLCD
 	select ARM_TIMER_SP804
 	select GPIO_PL061 if GPIOLIB
@@ -295,6 +297,7 @@
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select NEED_MACH_IO_H if PCI
 	select PLAT_VERSATILE
+	select PLAT_VERSATILE_CLOCK
 	select PLAT_VERSATILE_CLCD
 	select PLAT_VERSATILE_FPGA_IRQ
 	select ARM_TIMER_SP804
@@ -314,6 +317,7 @@
 	select ICST
 	select NO_IOPORT
 	select PLAT_VERSATILE
+	select PLAT_VERSATILE_CLOCK
 	select PLAT_VERSATILE_CLCD
 	help
 	  This enables support for the ARM Ltd Versatile Express boards.