Properly treat -ENOSYS as no PHY, else ehci-orion won't work without
generic phy support.

Backport of r46711.
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/chaos_calmer@46712 3c298f89-4303-0410-b956-a3cf2f4a3e73