media: sh_vou: Drop bogus __refdata annotation

Since commit 4c62e976 ("Drivers: media: remove __dev*
attributes.") in v3.8, the SuperH Video Output Unit driver no longer has
any code or data located in initmem, hence there is no need to annotate
the sh_vou structure with __refdata.  Drop the annotation, to avoid
suppressing future section warnings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>