uboot-imx

powerpc: Retain compatible property for L2 cache

When setting the compatible property for the L2 cache ensure that we
follow the documented binding by setting both
"<chip>-l2-cache-controller" and "cache" as values.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: York Sun <york.sun@nxp.com>