skip ballooning during migration

avoid to add memory load overhead on the migration with balloon inflate/deflate
Signed-off-by: Alexandre Derumier <aderumier@odiso.com>

PVE/AutoBalloon.pm

@@ -93,6 +93,7 @@ sub compute_alg1 {
 	my $d = $vmstatus->{$vmid};
 	next if !$d->{balloon}; # skip if balloon driver not running
 	next if !$d->{balloon_min}; # skip if balloon value not set in config
+	next if $d->{lock} &&  $d->{lock} eq 'migrate'; 
 	next if defined($d->{shares}) && 
 	    ($d->{shares} == 0); # skip if shares set to zero