drivers/cmsis-dap: port to common SWD framework

drivers/cmsis-dap: port to common SWD framework

Valgrind-tested.

Comparison of flashing performance on an FRDM-KL25Z board running mbed
CMSIS-DAP variant, 5MHz clock, old driver:

wrote 28096 bytes from file demo.elf in 26.833590s (1.023 KiB/s)
verified 27264 bytes in 1.754972s (15.171 KiB/s)

this implementation:

wrote 28096 bytes from file demo.elf in 3.691939s (7.432 KiB/s)
verified 27264 bytes in 0.598987s (44.450 KiB/s)

Also tested "Keil ULINK-ME CMSIS-DAP" with an STM32F100 target, 5MHz
clock, results reading from flash, old driver:

dumped 131072 bytes in 98.445305s (1.300 KiB/s)

this implementation:

dumped 131072 bytes in 8.242686s (15.529 KiB/s)

Change-Id: Ic64d3124b1d6cd9dd1016445bb627c71e189ae95
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2356
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>