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

[ Upstream commit 009808154c69c48d5b41fc8cf5ad5ab5704efd8f ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>