ARM: mach-mxs: Remove "TO" string from revision field

There is no need to print the silicon revision as "TO1.2", just print it as
"1.2" instead:

$ cat /sys/bus/soc/devices/soc0/revision
1.2

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>