aarch64: register access rewrite

aarch64: register access rewrite

All register access is now performed through common read/write
functions, which delegate the actual register access to the
armv8_common object. armv8_common contains function pointers
to direct read and write requests to the respective low-level
functions for each PE state.

The respective read/write functions are selected on debug state
entry.

At the same time, T32 opcodes are now formatted for ITR in
dpmv8_exec_opcode() and the T32_FMTITR macro is removed from global
visibility.

Change-Id: I9eaef017c7cc9e0c531e693c534901bfdbdb842c
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>