cmsis-dap: add initial cmsis-dap support

This is based on work from:
https://github.com/TheShed/OpenOCD-CMSIS-DAP/tree/cmsis-dap

Main changes include moving over to using HIDAPI rather than libusb-1.0
and cleaning up to merge into master. Support for reset using srst has
also been added.

It has been tested on all the mbed boards as well as the Freedom board
from Freescale. These boards only implement SWD mode, however JTAG mode
has been tested with a Keil ULINK2 and a stm32 target - but requires a lot
more work.

Change-Id: I96d5ee1993bc9c0526219ab754c5aad3b55d812d
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Signed-off-by: Andrey Yurovsky <yurovsky@gmail.com>
Reviewed-on: http://openocd.zylin.com/1542
Tested-by: jenkins

tcl/target/lpc17xx.cfg

@@ -49,10 +49,6 @@ if { [info exists CPUROMSIZE] } {
 	error "_CPUROMSIZE not set. Please do not include lpc17xx.cfg directly, but the specific chip configuration file (lpc1751.cfg, lpc1764.cfg, etc)."
 }
 
-#delays on reset lines
-adapter_nsrst_delay 200
-jtag_ntrst_delay 200
-
 #jtag newtap $_CHIPNAME cpu -irlen 4 -expected-id $_CPUTAPID
 swj_newdap $_CHIPNAME cpu -irlen 4 -expected-id $_CPUTAPID
 
@@ -74,6 +70,12 @@ flash bank $_FLASHNAME lpc2000 0x0 $_CPUROMSIZE 0 0 $_TARGETNAME \
 # we have no idea what clock the target is running at.
 adapter_khz 10
 
+# delays on reset lines
+adapter_nsrst_delay 200
+if {$using_jtag} {
+ jtag_ntrst_delay 200
+}
+
 $_TARGETNAME configure -event reset-init {
 	# Do not remap 0x0000-0x0020 to anything but the flash (i.e. select
 	# "User Flash Mode" where interrupt vectors are _not_ remapped,