media: include: v4l2-ctrl: Sort forward declarations

Before adding a new forward declaration to the v4l2-ctrls.h header file,
sort the existing ones alphabetically.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>