Add the target name to debug output for better understanding and error identification.

Change-Id: I1054debea6cd3a6548aadeae2d84000a0039814e
Signed-off-by: Mathias K <kesmtp@freenet.de>
Reviewed-on: http://openocd.zylin.com/1178
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>