staging: mt7621-dts: properly define 'cpc' and 'mc' nodes

'cpc' and 'mc' nodes correspond with the MIPS 'Cluster Power Controller'
and 'MIPS Common Device Memory Map' which are present in some MIPS related
boards. There is already bindings documentation for these two located in:
- Documentation/devicetree/bindings/power/mti,mips-cpc.yaml
- Documentation/devicetree/bindings/bus/mti,mips-cdmm.yaml

Hence, properly update compatible strings and align nodes with already
mainlined bindings documentation. Also, move their definition to a proper
place since both of them are not related with the palmbus at all.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20211002060706.30511-1-sergio.paracuellos@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>