scripts: checkpatch.pl: warn on invalid credentials

@quicinc.com identities are not allowed.  Check the "From:" field in the
patch, equivalent to the author in the git commit, and the Signed-off-by
field.

Signed-off-by: Bryan Huntsman <bryanh@codeaurora.org>
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
[imaund@codeaurora.org: Resolved context conflicts]
Signed-off-by: Ian Maund <imaund@codeaurora.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 943f794..c12276c 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2424,6 +2424,10 @@
 					     "email address '$email' might be better as '$suggested_email$comment'\n" . $herecurr);
 				}
 			}
+			if ($line =~ /^\s*signed-off-by:.*(quicinc|qualcomm)\.com/i) {
+				WARN("BAD_SIGN_OFF",
+				     "invalid Signed-off-by identity\n" . $line );
+			}			
 
 # Check for duplicate signatures
 			my $sig_nospace = $line;
@@ -2555,6 +2559,11 @@
 			     "added, moved or deleted file(s), does MAINTAINERS need updating?\n" . $herecurr);
 		}
 
+#check the patch for invalid author credentials
+		if ($line =~ /^From:.*(quicinc|qualcomm)\.com/) {
+			WARN("BAD_AUTHOR", "invalid author identity\n" . $line );
+		}
+
 # Check for wrappage within a valid hunk of the file
 		if ($realcnt != 0 && $line !~ m{^(?:\+|-| |\\ No newline|$)}) {
 			ERROR("CORRUPTED_PATCH",