ARM: mx53: Print silicon revision on boot

Having the silicon revision to appear on the boot log is a useful information.

MX31, MX35 and MX51 already show the silicon revision on boot.

Add support for displaying such information for MX53 as well.

Tested on a mx53loco board, where it shows:

CPU identified as i.MX53, silicon rev 2.0

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
LAKML-Reference: 1301068367-18937-1-git-send-email-fabio.estevam@freescale.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>