pinctrl: msm: make PINCTRL_MSM bool instead of tristate

Modular builds of pinctrl-msm break due to handle_bad_irq being
unexported for module use.  For now, make PINCTRL_MSM 'bool'.

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