powerpc/fadump: add source info while displaying region contents

Improve how fadump_region contents are displayed by adding source
information of memory regions that are to be dumped by f/w.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821334740.5656.5897097884010195405.stgit@hbathini.in.ibm.com
