The new firmwares for ST-Link support handling multiple AP, but
are (actually) limited to the AP number in range [0..8].
Any tentative to operate on AP number higher than 8 returns an
error "bad AP".
Add the error code and the related message.
Change-Id: I78a98b2612d10e580d03fc43ed9f2b09619d39d8
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4981
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins