The old ST-Link/V1 can either run an obsolete firmware with API_V1 or
a more recent firmware (from V1J11 to last V1J13) with API_V2.
SWD is only provided by the latter API.
Return error is SWD is selected on adapters that does not support it.
Change-Id: Iac4ba54d191ba80fb445a7cd3d8c2621dc7a4846
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4705
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>