remoteproc: st: Fix error return code in st_rproc_probe()

remoteproc: st: Fix error return code in st_rproc_probe()

commit 1d701d3dd8caf6660ff33c3c23a115b4649c5cdb upstream.

Fix to return a negative error code from the st_rproc_state() error
handling case instead of 0, as done elsewhere in this function.

Fixes: 63edb0310a5c ("remoteproc: Supply controller driver for ST's Remote Processors")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>