MLK-16067 tty: serial: lpuart: enable wakeup source in .suspend_noirq()

MLK-16067 tty: serial: lpuart: enable wakeup source in .suspend_noirq()

When use lpuart with DMA mode as wake up source, it still switch to
cpu mode in .suspend() that enable cpu interrupts RIE and ILIE as
wakkup source. When the wakeup signal coming while rx dma chan is
already teminated down, then driver should not call irq handler to
submit the new dma descriptor.

Enable the wakeup irq bits in .suspend_noirq() and disable the wakeup
irq bits in .resume_noirq().

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>