media: v4l2-subdev.h: v4l2_subdev_call: use temp __sd variable

The sd argument of this macro can be a more complex expression. Since it
is used 5 times in the macro it can be evaluated that many times as well.

So assign it to a temp variable in the beginning and use that instead.

This also avoids any potential side-effects of evaluating sd.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>