soc: msm: Move scm-xpu to outside of mach-msm into drivers

scm-xpu is required to be used by other ARCH.
Move it to drivers to facilitate this.

Change-Id: I38db64bdc830ec67016b6178867eaa4ce89f2ef3
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>