remoteproc: imx_rproc: support remote cores booted before Linux Kernel

 - When remote cores are kicked before Linux Kernel, we are not able
   to get resource table from the firmware elf file, so we need to add
   rsc_table to hold the resource table published by remote cores and
   imx_rproc_get_loaded_rsc_table is to get the resource table.
 - Per remoteproc framework, add attach hook for processor in a detached
   state.
 - Add imx_rproc_detect_mode to detect remote cores' working mode to
   set the state which is required by remoteproc framework.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1617846289-13496-5-git-send-email-peng.fan@oss.nxp.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>