remoteproc: imx_dsp_rproc: Make rsc_table optional

There are cases when we want to test a simple "hello world"
app on the DSP and we do not need a resource table.

remoteproc core allows us having an optional rsc_table.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20220331103237.340796-1-daniel.baluta@oss.nxp.com


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