USB: dwc3: fix runtime pm imbalance on unbind

USB: dwc3: fix runtime pm imbalance on unbind

Make sure to balance the runtime PM usage count on driver unbind by
adding back the pm_runtime_allow() call that had been erroneously
removed.

Fixes: 266d0493900a ("usb: dwc3: core: don't trigger runtime pm when remove driver")
Cc: stable@vger.kernel.org	# 5.9
Cc: Li Jun <jun.li@nxp.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20230404072524.19014-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>