tty: serial: imx: disable irq after suspend

If any key on console is pressed when board is suspended,
board hangs.

Driver's interrupt handler must be guaranteed not to run while
resume/suspend_noirq() are being executed. See include/linux/pm.h
for details.

Tested on i.MX6 based board.

The idea of this fix is based on commit in official i.MX kernel tree:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git


commit 81e8e7d91d81 ("tty: serial: imx: disable irq after suspend")

Disable rx irq after suspend to avoid interrupt coming in early resume.

Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Maxim Yu. Osipov <mosipov@ilbers.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>