msm: clock-8960: define reg_init for each target

Remove cpu checks from common reg_init function.

New functions introduced:
Each of these functions are called from target specific
 *_clock_pre_init function.
 1) 8960 --> reg_init_8960()
 2) 8930 --> reg_init_8930()
 3) 8064 --> reg_init_8064()

The below common functions are called from every target reg_init.
 4) enable_imem_clk() --> enables the imem clock. Argument passed are
 physical address and size.

 5) init_mm_cc() --> This function initializes the MM-CC registers which
 are again common to all targets. Each reg-init will take care of specific
 CC registers on their own.

Change-Id: If0bde2149f66237ace8cccf6a6f4c97ed561fc7f
Signed-off-by: Taniya Das <tdas@codeaurora.org>