usb: dwc2: Allow exit clock gating in urb enqueue

When core is in clock gating state and an external
hub is connected, upper layer sends URB enqueue request,
which results in port reset issue.

Added exit from clock gating state to avoid port
reset issue and process upper layer request properly.

Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@synopsys.com>
Link: https://lore.kernel.org/r/20210413073708.ADFC6A0094@mailhost.synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>