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: 63edb031 ("remoteproc: Supply controller driver for ST's Remote Processors")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

In order to be able to lock a rproc driver implementations only when
used by a client, we must differ between the dereference operation of a
client and the implementation itself.

This patch brings no functional change.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

syscon_regmap_lookup_by_phandle() returns either a valid pointer to
struct regmap or ERR_PTR() error value, check for NULL is invalid and
on error path may lead to oops, the change corrects the check.
Signed-off-by: NVladimir Zapolskiy <vz@mleia.com>
Acked-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Signed-off-by: NLudovic Barre <ludovic.barre@st.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>