util/scripts/get_maintainer.pl: Remove linux tree check

This was removed from the previous version, but we'd like it in
a separate patch, so it's obvious and can easily be applied to the
next version.

Change-Id: I9396009e82e762aa0cc037dbe9e7133962af6354
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/18577
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/scripts/get_maintainer.pl

@@ -297,11 +297,6 @@ if ($email &&
     die "$P: Please select at least 1 email option\n";
 }
 
-if (!top_of_kernel_tree($lk_path)) {
-    die "$P: The current directory does not appear to be "
-	. "a linux kernel source tree.\n";
-}
-
 ## Read MAINTAINERS for type/value pairs
 
 my @typevalue = ();