get_maintainer: use filename-only regex match for Tegra

Create a new N: entry type in MAINTAINERS which performs a regex match
against filenames; either those extracted from patch +++ or --- lines,
or those specified on the command-line using the -f option.

This provides the same benefits as using a K: regex option to match a
set of filenames (see commit eb90d0855b75 "get_maintainer: allow
keywords to match filenames"), but without the disadvantage that
"random" file content, such as comments, will ever match the regex.
Hence, revert most of that commit.

Switch the Tegra entry from using K: to N:

[[email protected]: fix typo in docs, per Marcin]
Reported-by: Marcin Slusarz <[email protected]>
Suggested-by: Joe Perches <[email protected]>
Signed-off-by: Stephen Warren <[email protected]>
Acked-by: Joe Perches <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/scripts/get_maintainer.pl b/scripts/get_maintainer.pl
index ce4cc83..5e4fb14 100755
--- a/scripts/get_maintainer.pl
+++ b/scripts/get_maintainer.pl
@@ -611,7 +611,7 @@
 				    $hash{$tvi} = $value_pd;
 				}
 			    }
-			} elsif ($type eq 'K') {
+			} elsif ($type eq 'N') {
 			    if ($file =~ m/$value/x) {
 				$hash{$tvi} = 0;
 			    }