msm: watchdog-v2: move watchdog driver to driver/soc/qcom

Architectural changes in the ARM Linux kernel tree mandate
the eventual removal of the mach-* directories. Move the
watchdog driver to drivers/soc/qcom

Change-Id: Ib938a0d2d1d0db50025a3f4e5aa0a48b1b1ecb87
Signed-off-by: Xiaogang Cui <xiaogang@codeaurora.org>
Signed-off-by: Aparna Das <adas@codeaurora.com>