adi_v5_swd: Improve SWD support

adi_v5_swd: Improve SWD support

Fix bug in parity calculation macro.

Cache and update the selected DP bank when necessary.

Add aborts when the Ack code signals a failure (we should really only
clear the sticky bits, but this will do for now).

Change-Id: I38a4da136ba1d9e989b33c1875a80c0b1b2be874
Signed-off-by: Fatih Aşıcı <fatih.asici@gmail.com>
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1950
Tested-by: jenkins