mp4: fix typo

Spotted by Christoph Miebach
(cherry picked from commit bc05fa41ed81614b1bdebc17b74ddcf4c7876760)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/demux/mp4/mp4.c

@@ -964,7 +964,7 @@ static int Control( demux_t *p_demux, int i_query, va_list args )
                 static const struct { uint32_t xa9_type; char metadata[25]; } xa9typetoextrameta[] =
                 {
                     { ATOM_0xa9wrt, N_("Writer") },
-                    { ATOM_0xa9com, N_("Composr") },
+                    { ATOM_0xa9com, N_("Composer") },
                     { ATOM_0xa9prd, N_("Producer") },
                     { ATOM_0xa9inf, N_("Information") },
                     { ATOM_0xa9dir, N_("Director") },