clk: versatile: Split config options for sp810 and vexpress_osc

Move the Kconfig entry for Versatile (& Express) clock drivers
into a separate file and add individual options for sp810
and vexpress_osc drivers, as they are optional in some
configurations and may have separate dependencies.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 6f56d3a..4fdfd6c 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -30,14 +30,7 @@
           Supports the clocking subsystem of the WM831x/2x series of
 	  PMICs from Wolfson Microlectronics.
 
-config COMMON_CLK_VERSATILE
-	bool "Clock driver for ARM Reference designs"
-	depends on ARCH_INTEGRATOR || ARCH_REALVIEW || ARCH_VEXPRESS || ARM64
-	---help---
-          Supports clocking on ARM Reference designs:
-	  - Integrator/AP and Integrator/CP
-	  - RealView PB1176, EB, PB11MP and PBX
-	  - Versatile Express
+source "drivers/clk/versatile/Kconfig"
 
 config COMMON_CLK_MAX77686
 	tristate "Clock driver for Maxim 77686 MFD"