remote processor may support:
 - boot recovery with help from main processor
 - self recovery without help from main processor
 - iommu
 - etc

Introduce rproc features could simplify code to avoid adding more bool
flags
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20220928064756.4059662-2-peng.fan@oss.nxp.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>