Check CMSIS-DAP adapter has serialnumber before pass it to wcscmp.
Keep looking for onother adapter if choosed one doesn't have correct
serialnumber.
Change-Id: I7d386a03cb49b9baf22073ae1c6b14269ed3b618
Signed-off-by: Andrii Anpilogov <anpilog@gmail.com>
Reviewed-on: http://openocd.zylin.com/3226
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>