drm/exynos: 'win' is always unsigned

The index for the hardware layer is always >=0. Previous
code that also used -1 as special index is now gone.

Also apply this to 'ch_enabled' (decon/fimd), since the
variable is on the same line (and is again always unsigned).

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos7_drm_decon.c b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
index 3d00df7..6714e5b 100644
--- a/drivers/gpu/drm/exynos/exynos7_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
@@ -91,7 +91,7 @@
 
 static void decon_clear_channel(struct decon_context *ctx)
 {
-	int win, ch_enabled = 0;
+	unsigned int win, ch_enabled = 0;
 
 	DRM_DEBUG_KMS("%s\n", __FILE__);