import.pl: temporarily add GR / 2R / MR prefixes for all UK&CD calls

todo: We should not need this at all on the long run. If there's a
G3AAA in the database, G*3AAA should automatically be recognized and
counted.

db/import.pl

@@ -44,7 +44,7 @@ while (my $line = <>) {
     }
     # Gx = GQ
     elsif ($callsign =~ /^([2GM])[A-Z]?(.*)/) {
-        $nc = "$1Q$2";
+        $nc = "$1R$2";
     }
 
     if ($nc and $left eq "20990101") {