usb: cdns3: Fix runtime PM imbalance on error

usb: cdns3: Fix runtime PM imbalance on error

BugLink: https://bugs.launchpad.net/bugs/1934012
[ Upstream commit 07adc0225484fc199e3dc15ec889f75f498c4fca ]

When cdns3_gadget_start() fails, a pairing PM usage counter
decrement is needed to keep the counter balanced.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/r/20210412054908.7975-1-dinghao.liu@zju.edu.cn
Signed-off-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>