checkpatch: improve the compatible vendor match

Improve the vendor name match in vendor-prefix.txt by only matching the
exact vendor name at the beginning of lines.
Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Cc: Joe Perches <joe@perches.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2080,9 +2080,11 @@ sub process {
 
 			my @compats = $rawline =~ /\"([a-zA-Z0-9\-\,\.\+_]+)\"/g;
 
+			my $dt_path = $root . "/Documentation/devicetree/bindings/";
+			my $vp_file = $dt_path . "vendor-prefixes.txt";
+
 			foreach my $compat (@compats) {
 				my $compat2 = $compat;
-				my $dt_path =  $root . "/Documentation/devicetree/bindings/";
 				$compat2 =~ s/\,[a-z]*\-/\,<\.\*>\-/;
 				`grep -Erq "$compat|$compat2" $dt_path`;
 				if ( $? >> 8 ) {
@@ -2090,14 +2092,12 @@ sub process {
 					     "DT compatible string \"$compat\" appears un-documented -- check $dt_path\n" . $herecurr);
 				}
 
-				my $vendor_path = $dt_path . "vendor-prefixes.txt";
-				next if (! -f $vendor_path);
 				next if $compat !~ /^([a-zA-Z0-9\-]+)\,/;
 				my $vendor = $1;
-				`grep -Eq "$vendor" $vendor_path`;
+				`grep -Eq "^$vendor\\b" $vp_file`;
 				if ( $? >> 8 ) {
 					WARN("UNDOCUMENTED_DT_STRING",
-					     "DT compatible string vendor \"$vendor\" appears un-documented -- check $vendor_path\n" . $herecurr);
+					     "DT compatible string vendor \"$vendor\" appears un-documented -- check $vp_file\n" . $herecurr);
 				}
 			}
 		}