remoteproc: qcom: hexagon: Fix error return code in q6v5_probe()

Fix to return a negative error code from the state get failed error
handling case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>