fix typo in frv endian comment

Reported-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

libc/sysdeps/linux/frv/bits/endian.h

@@ -1,4 +1,4 @@
-/* frv is little-endian.  */
+/* frv is big-endian.  */
 
 #ifndef _ENDIAN_H
 # error "Never use <bits/endian.h> directly; include <endian.h> instead."