tools: Make restore work properly with PV superpage flag

tools: Make restore work properly with PV superpage flag

For PV guests, the superpage flag means to unconditionally allocate all
pages as superpages, which is required for Linux hugepages to work.  Support
for this on restore was not supported.  This patch adds proper support for
the superpage flag on restore.

For HVM guests, the superpage flag has been used to mean attempt to allocate
superpages if possible on restore.  This functionality has been preserved.

Signed-off-by: Dave McCracken <dave.mccracken@oracle.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>