tty: serial: bcm: add lpm support

Conflicts:
	arch/arm/mach-msm/board-holiday.c
	arch/arm/mach-msm/board-pyramid.c
	arch/arm/mach-msm/board-shooter.c
	arch/arm/mach-msm/board-shooter_u.c
	drivers/tty/serial/msm_serial_hs.c