remoteproc: Introduce function __rproc_detach()

Introduce function __rproc_detach() to perform the same kind of
operation as rproc_stop(), but instead of switching off the
remote processor using rproc->ops->stop(), it uses
rproc->ops->detach().  That way it is possible for the core
to release the resources associated with a remote processor while
the latter is kept operating.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Link: https://lore.kernel.org/r/20210312162453.1234145-10-mathieu.poirier@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>