As this driver has been converted to DM_ETH and the migration deadline
is 2 years passed, remove the legacy code and callers.

Cc: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Acked-by: Ramon Fried <rfried.dev@gmail.com>