adiv5: introduce optional dap_sync() function

adiv5: introduce optional dap_sync() function

dap_sync() executes all commands in the JTAG queue and then checks
if a WAIT condition happened inside the last batch. If yes, a recovery
is invoked. If not, processing continues without checking for
errors. This function should be called in long AP read or writes, e.g.
while uploading a new application binary, at intermediate points within
the transfer where the cost of flushing the JTAG queue and checking the
journal doesn't affect performance too much.

Change-Id: I99eeaf47cdf951e15e589a04e74b90b5ce911386
Signed-off-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-on: http://openocd.zylin.com/3181
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>