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>

arch/arm/Kconfig

@@ -260,6 +260,7 @@ config ARCH_INTEGRATOR
 	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 @@ config ARCH_REALVIEW
 	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 @@ config ARCH_VERSATILE
 	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 @@ config ARCH_VEXPRESS
 	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.

arch/arm/plat-versatile/Kconfig

 if PLAT_VERSATILE
 
+config PLAT_VERSATILE_CLOCK
+	bool
+
 config PLAT_VERSATILE_CLCD
 	bool
 

arch/arm/plat-versatile/Makefile

-obj-y	:= clock.o
+obj-$(CONFIG_PLAT_VERSATILE_CLOCK) += clock.o
 obj-$(CONFIG_PLAT_VERSATILE_CLCD) += clcd.o
 obj-$(CONFIG_PLAT_VERSATILE_FPGA_IRQ) += fpga-irq.o
 obj-$(CONFIG_PLAT_VERSATILE_LEDS) += leds.o