drivers/net/ksz8864rmn: add driver for Micrel KSZ8864RMN Ethernet Switch
It starts the switch and provides basic access to the registers.
This driver could also work with some other Micrel switches, possibly
with some small changes.
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>