target: restructure dap support

- add 'dap create' command to create dap instances
- move all dap subcmmand into the dap instance commands
- keep 'dap info' for convenience
- change all armv7 and armv8 targets to take a dap
  instance instead of a jtag chain position
- restructure tap/dap/target relations, jtag tap no
  longer references the dap, daps are now independently
  created and initialized.
- clean up swd connect
- re-initialize DAP also on JTAG errors (e.g. after reset,
  power cycle)
- update documentation
- update target files

Change-Id: I322cf3969b5407c25d1d3962f9d9b9bc1df067d9
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>
Reviewed-on: http://openocd.zylin.com/4468
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

tcl/target/am437x.cfg

@@ -458,6 +458,7 @@ if { [info exists M3_DAP_TAPID] } {
 }
 jtag newtap $_CHIPNAME $M3_MODULE -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_M3_DAP_TAPID -disable
 jtag configure $M3_NAME -event tap-enable "icepick_d_tapenable $JRC_NAME 11 0"
+dap create $M3_NAME.dap -chain-position $M3_NAME
 
 #
 # DebugSS DAP
@@ -469,6 +470,7 @@ if { [info exists DAP_TAPID] } {
 }
 jtag newtap $_CHIPNAME $DEBUGSS_MODULE -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_DAP_TAPID -disable
 jtag configure $DEBUGSS_NAME -event tap-enable "icepick_d_tapenable $JRC_NAME 12 0"
+dap create $DEBUGSS_NAME.dap -chain-position $DEBUGSS_NAME
 
 #
 # ICEpick-D (JTAG route controller)
@@ -486,7 +488,7 @@ jtag configure $JRC_NAME -event post-reset "runtest 100"
 #
 # Cortex-A9 target
 #
-target create $_TARGETNAME cortex_a -chain-position $DEBUGSS_NAME -coreid 0 -dbgbase 0x80000000
+target create $_TARGETNAME cortex_a -dap $DEBUGSS_NAME.dap -coreid 0 -dbgbase 0x80000000
 
 
 # SRAM: 256K at 0x4030.0000