ARM: qcom: scm: Move the scm driver to drivers/soc/qcom

Architectural changes in the ARM Linux kernel tree mandate the eventual
removal of the mach-* directories. Move the scm driver to
drivers/soc/qcom and the scm header to include/soc/qcom to support that
removal.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>