Silicon revision is useful information to have during kernel boot.

Print the MX27 silicon revision.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NJason Liu <jason.hui@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>