clk: Add support for Arm's Versatile Express OSC clock generators

The Arm Versatile Express and Juno development boards contain an
OSC clock generator that can be accessed through the Versatile
Express config bus. The generators are quite often being controlled
by some MCU and the config bus offers a uniform way of exposing them.

Signed-off-by: Liviu Dudau <liviu.dudau@foss.arm.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index c996d65..7853a7a 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -68,6 +68,13 @@
 	help
 	  Enable this to support the cgu clocks on Synopsys ARC HSDK
 
+config CLK_VEXPRESS_OSC
+	bool "Enable driver for Arm Versatile Express OSC clock generators"
+	depends on CLK && VEXPRESS_CONFIG
+	help
+	  This clock driver adds support for clock generators present on
+	  Arm Versatile Express platforms.
+
 config CLK_ZYNQ
 	bool "Enable clock driver support for Zynq"
 	depends on CLK && ARCH_ZYNQ