gpio: msm: switch Kconfig to ARCH_QCOM depends

We've split Qualcomm MSM support into legacy and multiplatform.  The gpio
msm-v2 driver is only relevant on the multiplatform supported SoCs so
switch the Kconfig depends to ARCH_QCOM.

CC: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Kumar Gala <galak@codeaurora.org>