Blackfin: convert boards to use platform data with smc91x

Latest smc91x driver allows you to specify settings in board resources
rather than needing CONFIG_BLACKFIN in the drivers/net/smc91x.h header.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>