remoteproc: stm32: Constify st_rproc_ops

The only usage of st_rproc_ops is to pass its address to rproc_alloc()
which accepts a const pointer. Make it const to allow the compiler to
put it in read-only memory.
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20201107233630.9728-3-rikard.falkeborn@gmail.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/stm32_rproc.c

@@ -541,7 +541,7 @@ static void stm32_rproc_kick(struct rproc *rproc, int vqid)
 	}
 }
 
-static struct rproc_ops st_rproc_ops = {
+static const struct rproc_ops st_rproc_ops = {
 	.start		= stm32_rproc_start,
 	.stop		= stm32_rproc_stop,
 	.attach		= stm32_rproc_attach,