powerpc/fsl: Fix rcpm compatible string

For T1040, T1042, T1023, and T1024, they should use the compatible
string "fsl,qoriq-rcpm-2.1".

Signed-off-by: Chenhui Zhao <chenhui.zhao@nxp.com>
Signed-off-by: Scott Wood <oss@buserror.net>