phy: renesas: rcar-gen3-usb2: exit if request_irq() failed

To avoid unexpected behaviors, it's better to exit if request_irq()
failed.

Suggested-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/1594986297-12434-3-git-send-email-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>