video: ipu: prevent warnings with W=1

- make local functions static
- remove unused is_interlaced function

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/drivers/video/mxc_ipuv3_fb.c b/drivers/video/mxc_ipuv3_fb.c
index b20c19c..1fa9531 100644
--- a/drivers/video/mxc_ipuv3_fb.c
+++ b/drivers/video/mxc_ipuv3_fb.c
@@ -36,7 +36,7 @@
 static uint8_t gdisp;
 static uint32_t gpixfmt;
 
-void fb_videomode_to_var(struct fb_var_screeninfo *var,
+static void fb_videomode_to_var(struct fb_var_screeninfo *var,
 			 const struct fb_videomode *mode)
 {
 	var->xres = mode->xres;