Add a new udbg driver for the PS3 gelic Ehthernet device.

This driver shares only a few stucture and constant definitions with the
gelic Ethernet device driver, so is implemented as a stand-alone driver
with no dependencies on the gelic Ethernet device driver.
Signed-off-by: NHector Martin <hector@marcansoft.com>
Signed-off-by: NAndre Heider <a.heider@gmail.com>
Signed-off-by: NGeoff Levand <geoff@infradead.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>