usb: gadget: renesas_usbf: Handle devm_pm_runtime_enable() errors

usb: gadget: renesas_usbf: Handle devm_pm_runtime_enable() errors

devm_pm_runtime_enable() can fail due to memory allocation.
The current code ignores its return value, potentially causing
pm_runtime_resume_and_get() to operate on uninitialized runtime
PM state.

Check the return value of devm_pm_runtime_enable() and return on failure.

Fixes: 3e6e14ffdea4 ("usb: gadget: udc: add Renesas RZ/N1 USBF controller support")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Acked-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251124022215.1619-1-vulab@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>