serial: of-serial: fix up PM ops on no_console_suspend and port type

This patch fixes commit 2dea53bf

,
"serial: of-serial: add PM suspend/resume support", which disables
the uart clock on suspend, but also causes a hardware hang on register
access if no_console_suspend command line option is used.

Also, not every of_serial device is an 8250 port, so the serial8250
suspend/resume functions should only be applied to a real 8250 port.

Signed-off-by: Jingchang Lu <jingchang.lu@freescale.com>
Tested-by: Joseph Lo <josephl@nvidia.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>