b44: power down PHY when interface down

This is just this patch (http://lkml.org/lkml/2007/7/1/51) but adapted
to the 'b44' ssb driver.

Signed-off-by: Miguel Botón <mboton@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed