fix segfault from stack corruption in ahbap_debugport_init

fix segfault from stack corruption in ahbap_debugport_init

ahbap_debugport_init was queueing reads to a local stack variable but
didn't execute the queue before returning. Since the result of the reads
are not used anyway, it's better to pass NULL as the destination instead of
a dummy variable. I changed this throughout the function, even for the
reads that were actually executed.

Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Signed-off-by: Spencer Oliver <ntfreak@users.sourceforge.net>