ARM11: tweak TAP ops and debugging

ARM11: tweak TAP ops and debugging

Tweak scanchain 7 debug messaging:

 - show register addresses in decimal, matching ARM docs;
 - remove some pointless noise

Avoid some needless roundtrips:

 - skip SCAN_N when SCREG already holds that number (speeds up
   polling and other common operations)
 - avoid zeroing vcr twice on resume

Show the IR opcode as a label ("RESTART") too; and in decimal,
matching ARM docs.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>