msm_serial_hs: Cleanup code to configure/unconfigure UART GPIOs

With current approach UART GPIOs are configure/unconfigure from
board files by using GPIOLib APIs. UART driver uses gpio_config
pdata based function pointer to call per uart device related API
from board file for the same. Hence correct this approach and
pass only UART GPIOs numbers to UART driver using pdata and
configure/unconfigure those GPIOs using GPIOLib APIs once UART
port is being opened and closed respectively.

CRs-Fixed: 460961
Change-Id: I4bb007b2b476525cb50dd2eb5788c735aae0e32d
Signed-off-by: Mayank Rana <mrana@codeaurora.org>