MIPS: DTS: JZ4780: define node for JZ4780 efuse

This patch brings support for the JZ4780 efuse. Currently it only exposes
a read only access to the entire 8K bits efuse memory and the
ethernet mac address for the davicom dm9000 chip on the CI20 board.

It also changes the nemc ranges definition to give the driver
access to the efuse registers, which are in the middle of the
nemc reg range.

Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>