Staging: dt3155: rename dt3155_config_s

Drop the "_s", as it's not needed.

Now, dt3155.h is checkpatch.pl clean.

Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Scott Smedley <ss@aao.gov.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>