phy: ath79-usb: Fix the power on error path

In the power on function the error path doesn't return the suspend
override to its proper state. It should should deassert this reset
line to enable the suspend override.

Signed-off-by: Alban Bedel <albeu@free.fr>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>