ARM: shmobile: rcar-gen2: Initialize CCF before clock sources

When CONFIG_COMMON_CLOCK is enabled, call rcar_gen2_clocks_init() in the
timer init function to initialize the common clock framework before
initializing the clock sources. This will take care of clock
initialization when the r8a779[01] boards will be switched to
multiplatform kernels.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>