msm: qpnp-misc: add support to configure PWM source

Add the qcom,pwm-sel and qcom,enable-gp-driver properties to
the MISC device driver to enable configuring the PWM source.
Currently this will be supported only for pmdcalifornium.

CRs-Fixed: 972331
Change-Id: I320edac22b20d748a531a41eaff06162092cfd3d
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>