serial: msm_geni_serial: Add support for active pinctrl state

This change helps configuring GPIO to non UART function which makes
them to stay low when not in use. Kernel framework considers default
state to configure GPIOs during probe.

Adding active pinctrl node for the active configuration set and current
default configuration will be used during the probe time.

Change-Id: Ib26b36876b9c69971dcfe723b269e50026f87e82
Signed-off-by: Akash Asthana <akashast@codeaurora.org>