Updated yaffs signature

src/binwalk/magic/filesystems

@@ -34,7 +34,11 @@
 #>0x1e   string      minix       \b, bootable
 
 # YAFFS
-0    string    \x03\x00\x00\x00\x01\x00\x00\x00\xFF\xFF    YAFFS filesystem
+0    string     \x03\x00\x00\x00\x01\x00\x00\x00\xFF\xFF\x00\x00    YAFFS filesystem, little endian
+# The big endian signature has to be done a bit differently to prevent it from being self-overlapping
+4    string     \x00\x00\x00\x01\xFF\xFF                            YAFFS file system, big endian
+>0   string     !\x00\x00\x00\x03                                   {invalid}(first object is not a directory)
+>10  string     !\x00                                               {invalid}(unexpected name in the first object entry)
 
 # EFS2 file system - jojo@utulsa.edu
 0      lelong       0x53000000       EFS2 Qualcomm filesystem super block, little endian,