[media] s5p-tv: Add missing braces around sizeof in mixer_video.c

Silences several checkpatch warnings of the type:
WARNING: sizeof *out should be sizeof(*out)
FILE: media/platform/s5p-tv/mixer_video.c:98:
		out = kzalloc(sizeof *out, GFP_KERNEL);

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>