msm_serial_hs: fix suspend state handle

For the platforms that use pinctrl, unconfigure
the UART GPIOs appropriately by calling the correct
pinctrl APIs.

Change-Id: I2c541f2bbe0126c097662196c2f0b89977d55efc
Signed-off-by: Sungjun Park <sjpark@codeaurora.org>
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>