clk: sprd: Select REGMAP_MMIO to avoid compile errors

Make REGMAP_MMIO selected to avoid undefined reference to regmap symbols.

Fixes: d41f59f ("clk: sprd: Add common infrastructure")
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/sprd/Kconfig

@@ -3,6 +3,7 @@ config SPRD_COMMON_CLK
 	tristate "Clock support for Spreadtrum SoCs"
 	depends on ARCH_SPRD || COMPILE_TEST
 	default ARCH_SPRD
+	select REGMAP_MMIO
 
 if SPRD_COMMON_CLK