gpio_msm: Move Qualcomm MSM v2 gpio driver into drivers

Migrate the driver for the v7-based MSM chips into drivers/gpio.  The
driver is unchanged, only moved.

Change-Id: I810db5b50b71cdca4e869aa0d0310f7f48781a55
Signed-off-by: David Brown <davidb@codeaurora.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>