media: staging: media: zoran: Fixes a checkpatch.pl error in videocodec.c

ERROR: do not initialise statics to NULL

Signed-off-by: claudiojpaz <claudiojpaz@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>