PM / devfreq: sun8i: addd COMMON_CLK dependency

PM / devfreq: sun8i: addd COMMON_CLK dependency

Compile-testing the driver without CONFIG_COMMON_CLK causes
a link failure:

arm-linux-gnueabi-ld: drivers/devfreq/sun8i-a33-mbus.o: in function `sun8i_a33_mbus_remove':
sun8i-a33-mbus.c:(.text+0x450): undefined reference to `clk_rate_exclusive_put'
arm-linux-gnueabi-ld: sun8i-a33-mbus.c:(.text+0x460): undefined reference to `clk_rate_exclusive_put'
arm-linux-gnueabi-ld: drivers/devfreq/sun8i-a33-mbus.o: in function `sun8i_a33_mbus_probe':
sun8i-a33-mbus.c:(.text+0x85c): undefined reference to `clk_rate_exclusive_get'
arm-linux-gnueabi-ld: sun8i-a33-mbus.c:(.text+0x878): undefined reference to `clk_rate_exclusive_get'

Fixes: 8bfd4858b4bb ("PM / devfreq: Add a driver for the sun8i/sun50i MBUS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>