Remove lots of no-op or dummy info function implementations and check if
it's implemented before invoking it.
Change-Id: I2144dad6a84a80359bb13a8a29a4614387e4c135
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1642
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>