Fix the return value check typo which testing the wrong variable
in ingenic_usb_phy_probe().

Fixes: 31de313d ("PHY: Ingenic: Add USB PHY driver using generic PHY framework.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210305034933.3240914-1-weiyongjun1@huawei.comSigned-off-by: Vinod Koul <vkoul@kernel.org>