NULL check before dereferencing

NULL check before dereferencing

Check reg_list[i]->feature for NULL pointers before checking feature->name
in order to avoid NULL access.

Change-Id: If20401a6c5aa5e1e29f0fcf9bb95585b49658832
Signed-off-by: Luca BRUNO <lucab@debian.org>
Reviewed-on: http://openocd.zylin.com/1809
Tested-by: jenkins
Reviewed-by: Peter Stuge <peter@stuge.se>
Reviewed-by: Jens Bauer <jens@gpio.dk>