serial: fsl-lpuart: add lpuart32 power management support

This adds 32-bit register lpuart32 power management support,
this also updates the 8-bit register lpuart resume function.

Signed-off-by: Jingchang Lu <jingchang.lu@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>