remoteproc: Merge table_ptr and cached_table pointers

As all vdev resources are allocated before we boot the remote processor
we no longer need to support modifying the resource table while the
remote is running.

This saves us from the table_ptr dance, but more importantly allow the
remote processor to enable security lock down of the loaded table memory
region.

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