audit: use data= not msg= for AUDIT_USER_TTY messages

Userspace parsing libraries assume that msg= is only for userspace audit
records, not for user tty records.  Make this consistent with the other
tty records.

Reported-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/kernel/audit.c b/kernel/audit.c
index 02a5d9e..c45e6d2 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -755,7 +755,7 @@
 			else {
 				int size;
 
-				audit_log_format(ab, " msg=");
+				audit_log_format(ab, " data=");
 				size = nlmsg_len(nlh);
 				if (size > 0 &&
 				    ((unsigned char *)data)[size - 1] == '\0')