All pages which are going to be migrated are first added to
MultiFDSendParams::MultiFDPages_t::offset array by the main migration
thread and are subsequently copied to MultiFDSendParams::normal by the
multifd thread. This is really unnecessary as the MultiFDPages_t is
guaranteed to be stable since its mutex is being held. Additionally,
this somewhat simplifies the code as the migration pages are now kept
in only 1 place during send, also the name 'offset' coupled with the
context it's being used - usually added to the host pages makes it
obvious that this is an offset.
With this change normal/normal_num are no longer used in the multifd
send path.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>