str9: ignore boundary scan version

Ignore version of Boundary Scan TAP in newer revisions of the str9.

Change-Id: I6e205f8c731f07078c469e686025857c180f3a6d
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1436
Tested-by: jenkins