"I cannot access the variable" is a very very unfortunate description of what you want to do.

$svr is declared with "my", so it's lexical. Here, you will only find it in your for-loop. Try:

for my $svr (<SERVERLST>) {
   chomp $svr;
   ls_engine ($svr);
}
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And read up in 'perldoc perlsub' about what & actually does.