usb: dwc3: xilinx: improve error handling for PM APIs

Improve error handling for PM APIs in the dwc3_xlnx_probe function by
introducing devm_pm_runtime_enable and error label. Removed unnecessary
API pm_runtime_disable call in dwc3_xlnx_remove.

Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://lore.kernel.org/r/1700590878-124335-1-git-send-email-radhey.shyam.pandey@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>