In case of error, the function usb_phy_generic_register()
returns ERR_PTR() and never returns NULL. The NULL test in
the return value check should be replaced with IS_ERR().
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NPeter Chen <peter.chen@nxp.com>