adi_v5: Fix wrong ap value

adi_v5: Fix wrong ap value

Problem
dap->ap_current is register value, not field value.
it restores invalid ap when it calls dap_ap_select(dap, ap_old) later.

* assume the current ap is 1, dap->ap_current value would be (1 << 24).
ap_old = dap->ap_current;   <-- ap_old = 1<<24 = 0x1000000.
...
dap_ap_select(dap, ap_old); <-- select 0x1000000, not 1.
* All AP registers accessing fail afterwards.

One of the reproducible case(s): CORE residents in AP >= 1
  dap_lookup_cs_component() being used to find PE(*).
  In most cases, PE would be found in AP==0, hence the problem is hidden.
  When AP number is 1, dap->ap_current would have the value of 1<<24.
  Anyone get the AP value with dap->ap_current and resotre it later would
  select the wrong AP and all accessing later would fail.

  The ARM Versatile and/or FPGA would have better chance to provide this
  kind of environment that PE residents in AP>=1. As they have an 'umbrella'
  system at AP0, and main system at AP>=1.

  * PE: Processing Element. AKA Core. See ARM Glossary at
    http://infocenter.arm.com/help/topic/com.arm.doc.aeg0014g/ABCDEFGH.html

Fix
Use dap_ap_get_select() to get ap value.
a. Retrieve current ap value by calling dap_ap_get_select();
     src/flash/nor/kinetis.c
     src/target/arm_adi_v5.c

b. The code is correct (dap->ap_current >> 24), but it's better to use
   dap_ap_get_select() so everything could be synchronized.
     src/flash/nor/sim3x.c

Change-Id: I97b5a13a3fc5506cf287e299c6c35699374de74f
Signed-off-by: Alamy Liu <alamy.liu@gmail.com>
Reviewed-on: http://openocd.zylin.com/2935
Reviewed-by: Andreas Färber <afaerber@suse.de>
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>