Convert CS8900 Ethernet driver to CONFIG_NET_MULTI API

All in-tree boards that use this controller have CONFIG_NET_MULTI added
Also:
  - changed CONFIG_DRIVER_CS8900 to CONFIG_CS8900
  - changed CS8900_BASE to CONFIG_CS8900_BASE
  - changed CS8900_BUS?? to CONFIG_CS8900_BUS??
  - cleaned up line lengths
  - modified VCMA9 command function that accesses the device
  - removed MAC address initialization from lib_arm/board.c

Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
Tested-by: Wolfgang Denk <wd@denx.de>
Acked-by: Wolfgang Denk <wd@denx.de>