spi/imx: Add i.MX53 support

1. Change the Kconfig to include i.MX53
2. add devtype entry for i.MX53

Signed-off-by: Yong Shen <yong.shen@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>