Fix MX51 CPU detect message.
Original string was:
CPU: Freescale i.MX51 family 3.0V at 800 MHz
which can be misinterpreted as 3.0 Volts instead of the silicon revision.
,change it to:
CPU: Freescale i.MX51 family rev3.0 at 800 MHz
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>