dt-bindings: remoteproc: stm32-rproc: Typo fix

Fix "communnication" typo error.

Fixes: aca8f94e ("dt-bindings: remoteproc: stm32-rproc: add new mailbox channel for detach")
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
[Fixed title to read "stm32-rproc" instead of "st,stm32-rproc"]
Link: https://lore.kernel.org/r/20230403162423.3325968-1-arnaud.pouliquen@foss.st.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>