tools/xc_restore: Initialise console and store mfns

tools/xc_restore: Initialise console and store mfns

If the console or store mfn chunks are not present in the migration stream,
stack junk gets reported for the mfns.

XenServer had a very hard to track down VM corruption issue caused by exactly
this issue.  Xenconsoled would connect to a junk mfn and incremented the ring
pointer if the junk happend to look like a valid gfn.

Coverity ID: 1056093 1056094

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>