remoteproc: Add firmware checksum resource entry

remoteproc: Add firmware checksum resource entry

Add a firmware checksum resource entry type to store the checksum
of the firmware in the resource table.

In the remoteproc driver firmware booting process, it can check
if the remote already runs the expected firmware so that it can
decide if it needs to restart the remote if the remote already
runs.

Signed-off-by: Wendy Liang <jliang@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>