[ARM] versatile: convert to clkdev and lookup clocks by device name

People often point to the Integrator/Versatile/Realview
implementations to justify using the consumer name as the sole
selector for clocks.

Eliminate this excuse by changing the Versatile implementation, so
it provides a better example of how it should be done.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index f1ac393..75f0319 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -231,6 +231,7 @@
 	select ARM_AMBA
 	select ARM_VIC
 	select HAVE_CLK
+	select COMMON_CLKDEV
 	select ICST307
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS