Fixes one sparse warning:
  mxl5xx.c:46:1: warning: symbol 'mxllist' was not declared. Should it be static?
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>