net/phy: Fix copper/fiber auto-selection for 88e1111

The 27.15 bit (MII_M1111_HWCFG_FIBER_COPPER_AUTO) is disable bit. When
set to 1, copper/fiber auto selection is disabled. The current code
to enable but actually disable auto selection.

Signed-off-by: Wang Jian <lark@linux.net.cn>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>