riscv: dts: microchip: fix disco kit phy node address warnings

commit f029aa881cf65e64651d617cbca1141042c5fa39 from
https://github.com/linux4microchip/linux.git

 linux-6.6-mchp+fpga

The bindings require that the node address be in hex. Fix the node
address and make the reg property hex also to match.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: harish h <harish.h@windriver.com>