[build] Remove nested "my" declaration

Fix build error with perl >= 5.23.2:

  Can't redeclare "my" in "my" at ./util/parserom.pl line 160

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/util/parserom.pl

 
 # Output Makefile rules for the specified ROM declarations
 sub print_make_rules {
-    my ( $state, my $image, my $desc, my $vendor, my $device, my $dup ) = @_;
+    my ( $state, $image, $desc, $vendor, $device, $dup ) = @_;
     unless ( $state->{'is_header_printed'} ) {
         print "# NIC\t\n";
         print "# NIC\tfamily\t$state->{family}\n";