remoteproc: imx_dsp_rproc: Add module parameter to ignore ready flag from remote processor

There are cases when we want to test a simple "hello world"
application on the DSP and we don't have IPC between the cores.
Therefore, do not wait for a confirmation from the remote processor
at start.

Added "no_mailboxes" flag while inserting the module to not initialize
any mailboxes, and so ignore remote processor reply after start.
By default, this is off - do not ignore reply from rproc.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20230217094124.9440-1-iuliana.prodan@oss.nxp.com
[Fixed checkpatch warning]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>