tools: zynqmpimage: Add partition read support

tools: zynqmpimage: Add partition read support

The zynqmp image format has support for inline partitions which are
used by FSBL to describe payloads that are loaded by FSBL itself.

While we can't create images that contain partitions (yet), we should
still at least be able to examine them and show the user what's inside
when we analyze an image created by bootgen.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>