When entering deep sleep, the value in the registers I2CFDR and
I2CDFSRR are lost. This causes I2C access to fail after resuming.

Add suspend/resume routines to save/restore the registers
I2CFDR and I2CDFSRR.
Signed-off-by: NZhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: NLi Yang <leoli@freescale.com>
Signed-off-by: NWolfram Sang <w.sang@pengutronix.de>