usb: dwc3-msm: Cleanup suspend and resume functions

There are many variables and checks which are now redundant
on newer platforms in dwc3_msm_suspend() and dwc3_msm_resume()
functions. Hence remove them and cleanup these functions.

Change-Id: I8ca6a64e60d73550d560fba8244ab0208721778b
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>