clock: max77686: Add driver for Maxim 77686 32Khz crystal oscillator.

This patch supports max77686 mfd's clock driver using common clock frame work.
max77686 has 3 clock ouputs which all are generated from crystal oscillator and
SOC can enable/disable them via I2C bus. All clocks are fixed-rate clock sources
so that it doesn't supply interface for changing clock rate.
Driver uses regmap API to communicate with internal register.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d561825..6327536 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -19,3 +19,4 @@
 
 # Chip specific
 obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
+obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o