arm_debug: Support multiple APs per DAP and remove DAP from armv7* structs

arm_debug: Support multiple APs per DAP and remove DAP from armv7* structs

Separate out the values from adiv5_dap that are associated with a specific AP into a new struct, so we can properly support multiple APs. Remove the DAP struct from the armv7* structs, because we can have multiple CPUs per DAP, and we shouldn't have multiple DAP structs. Tidy up a few places where ap_current is used incorrectly.

Change-Id: I0c6ef4b49cc86b140366347aaf9b76c07cbab0a8
Signed-off-by: Patrick Stewart <patstew@gmail.com>
Reviewed-on: http://openocd.zylin.com/2984
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>