Blackfin: add blackfin support in smc91x ethernet controller driver

As SMC91X ethernet controller are used in blackfin STAMP 533 development
board, this patch add blackfin support to the smc91x linux driver.

Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>