Fix Ubiquiti partiton PART and END headers

The zero-padding used to identify the PART and END headers is not part
of the header itself but rather padding from previous data structures.
That is totally fine since the padding will always be there when
analyzing Ubiquiti firmware images.

src/binwalk/magic/firmware

@@ -453,16 +453,16 @@
 >4      byte        0           {invalid},
 >4      string      x           version: "%s"
 
-4   string      \x00\x00\x00\x00PART    Ubiquiti partition header,
+-4  string      \x00\x00\x00\x00PART    Ubiquiti partition header,
 >0  byte        x                       header size: 56 bytes,
->8  byte        0                       {invalid}
->8  string      x                       name: "%s",
->44 ubelong     x                       base address: 0x%.8X,
->52 belong      x                       data size: %d bytes{size:%d}
-
-4   string      \x00\x00\x00\x00END\x2e Ubiquiti end header, header size: 12 bytes,
->12 belong      !0                      {invalid},
->8  ubelong     x                       cumulative ~CRC32: 0x%.8X
+>0  byte        0                       {invalid}
+>0  string      x                       name: "%s",
+>40 ubelong     x                       base address: 0x%.8X,
+>48 belong      x                       data size: %d bytes{size:%d}
+
+-4  string      \x00\x00\x00\x00END\x2e Ubiquiti end header, header size: 12 bytes,
+>8  belong      !0                      {invalid},
+>4  ubelong     x                       cumulative ~CRC32: 0x%.8X
 
 
 # Found in DIR-100 firmware