remoteproc: qcom: Use PTR_ERR_OR_ZERO

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>