V4L/DVB: v4l2-common: Move v4l2_find_nearest_format from videodev2.h to v4l2-common.h

This function is an internal API and belongs in v4l2-common.h, not
videodev.h. The return pointer and probe argument should be const as well.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index 31ae1a1..cef80da 100644
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -677,12 +677,13 @@
 }
 EXPORT_SYMBOL_GPL(v4l_fill_dv_preset_info);
 
-struct v4l2_frmsize_discrete *v4l2_find_nearest_format(struct v4l2_discrete_probe *probe,
-						       s32 width, s32 height)
+const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(
+		const struct v4l2_discrete_probe *probe,
+		s32 width, s32 height)
 {
 	int i;
 	u32 error, min_error = UINT_MAX;
-	struct v4l2_frmsize_discrete *size, *best = NULL;
+	const struct v4l2_frmsize_discrete *size, *best = NULL;
 
 	if (!probe)
 		return best;