pinctrl: msm: switch to using generic GPIO irqchip helpers

This switches the Qualcomm MSM pin control driver over to using
the generic GPIO irqchip helpers.

Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Acked-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>