TT#83313 lnp rounting_number csv NULL values

kamailio fails with empty strings instead of NULL
for rounting_number values.

Change-Id: Ie79b9e9f9bba2c8419a0d637ac03495f871bea20

lib/NGCP/Panel/Utils/Lnp.pm

@@ -136,6 +136,7 @@ sub upload_csv {
             push @fails, $linenum;
             next;
         }
+        $row->{routing_number} = undef if (defined $row->{routing_number} and $row->{routing_number} eq '');
         push @numbers, [$carriers{$k}, $row->{number}, $row->{routing_number}, $row->{start}, $row->{end}, $row->{type}];
 
         if($linenum % $chunk_size == 0) {