riscv: dts: microchip: Use 'local-mac-address' for emac1

Per the DT spec, 'local-mac-address' is used to specify MAC address
that was assigned to the network device, while 'mac-address' is used
to specify the MAC address that was last used by the boot program,
and shall be used only if the value differs from 'local-mac-address'
property value.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: conor dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>