Revert "dwc3-msm: Add support to vote USB FORCE_MEM_CORE_ON"

This change reverts commit ("f1984dce dwc3-msm: Add support to vote
USB FORCE_MEM_CORE_ON") which is using dummy clock to update USB
master clock for keeping USB controller CSR retain while going into
CXPC. There is new API qcom_clk_set_flags() propose which supports
same functionality without USB dummy clock.

Change-Id: I0e35e4dac265a22eac2c3e95946cc9171c309508
Signed-off-by: Mayank Rana <mrana@codeaurora.org>