mtd: mxc_nand: dont call suspend and resume explicitly

The mtd layer is responsible to call mtd->{suspend,resume}.  Doing it
again in the driver is wrong and results in a warning:

	nand_resume called for a chip which is not in suspended state

at resume time.  Removing the calls from the resume and suspend
functions makes them empty allowing them to be deleted completely.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>