[ARC] Add deep packet inspection instructions for nps

With the exception of ldbit, this commit adds implementations of
all DPI instructions for the NPS-400. These instructions are:

- hash / hash.p[0-3]
- tr
- utf8
- e4by
- addf

include/opcode/arc.h

@@ -49,6 +49,7 @@ typedef enum
     BITOP,
     NET,
     ACL,
+    DPI,
   } insn_class_t;
 
 /* Instruction Subclass.  */