For Ethernet PHYs that don't have an IRQ pin or boards that don't
connect the IRQ pin to the processor, we enable a timer to poll the
PHY's link state.

Patch originally supplied by Eric Benard and Roman Kolesnikov.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>