Staging: dwc2: Fix return error value in dwc2_driver_probe()

This patch fixes the following smatch warning in platform.c-
drivers/staging/dwc2/platform.c:109 dwc2_driver_probe() info: why not propagate 'irq' from platform_get_irq() instead of (-22)?

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>