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/lpc1850.cfg

@@ -23,9 +23,10 @@ if { [info exists M3_JTAG_TAPID] } {
 }
 
 swj_newdap $_CHIPNAME m3 -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_M3_JTAG_TAPID
+dap create $_CHIPNAME.dap -chain-position $_CHIPNAME.m3
 
 set _TARGETNAME $_CHIPNAME.m3
-target create $_TARGETNAME cortex_m -endian $_ENDIAN -chain-position $_TARGETNAME
+target create $_TARGETNAME cortex_m -endian $_ENDIAN -dap $_CHIPNAME.dap
 
 if {![using_hla]} {
    # if srst is not fitted use SYSRESETREQ to