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

src/target/arm_adi_v5.c

@@ -664,6 +664,8 @@ int ahbap_debugport_init(struct adiv5_dap *dap)
 
 	/* DP initialization */
 
+	dap->dp_bank_value = 0;
+
 	retval = dap_queue_dp_read(dap, DP_CTRL_STAT, NULL);
 	if (retval != ERROR_OK)
 		return retval;