In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().

Fixes: 2fc305be ("usb: chipidea: msm: Mux over secondary phy at the
right time")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: NStephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: NPeter Chen <peter.chen@nxp.com>