opflags: Rework opflags bits with OP_ macros

opflags: Rework opflags bits with OP_ macros

In this path the opflags bits are completely reworked
in a sake of simplier extension. Inparticular for Knights
Corener instructions we will need new registers and new
sizes.

What's done

 - all bits are grouped in sequences, and start using OP_
   macros, thus if one need to extend some field -- just
   tune up @shift and @bits where needed

 - the #define we use in code are OR'ed in symbols, this
   should be a way more convenient to deal with instead of
   pure hex numbers.

The tests are passed but more eyes needed to review this
rather big and intrusive patch. The reason why it's done
in one single path -- for revertability in one command.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>