msm: clock-8960: cleanup of clock_pre_init function

Each target now has it's own pre_init hook, so soc/cpu checks
in the 8960_clock_pre_init are now removed. Each target's pre_init
function now has cpu checks to differentiate any feature.

1) 8960 --> 8960_clock_pre_init
2) 8930 --> __msm8930_clock_pre_init
3) 8064 --> msm8064_clock_pre_init

Change-Id: I950a01cafc1ddacd4db4b9add7e9a58a220e3a2b
Signed-off-by: Taniya Das <tdas@codeaurora.org>