imx: mx27 implement get_cpu_rev

Implement get_cpu_rev to support runtime check using is_cpu_type.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Stefano Babic <sbabic@denx.de>
1 file changed