drm/imx: Make pipe number unsigned

There's no reason whatsoever why this should ever be negative. The same
goes for the number of pipes added to the DRM device.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178476-26284-4-git-send-email-boris.brezillon@free-electrons.comSigned-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/imx/imx-drm-core.c

@@ -39,13 +39,13 @@ struct imx_drm_component {
 struct imx_drm_device {
 	struct drm_device			*drm;
 	struct imx_drm_crtc			*crtc[MAX_CRTC];
-	int					pipes;
+	unsigned int				pipes;
 	struct drm_fbdev_cma			*fbhelper;
 };
 
 struct imx_drm_crtc {
 	struct drm_crtc				*crtc;
-	int					pipe;
+	unsigned int				pipe;
 	struct imx_drm_crtc_helper_funcs	imx_drm_helper_funcs;
 };
 
@@ -54,7 +54,7 @@ static int legacyfb_depth = 16;
 module_param(legacyfb_depth, int, 0444);
 #endif
 
-int imx_drm_crtc_id(struct imx_drm_crtc *crtc)
+unsigned int imx_drm_crtc_id(struct imx_drm_crtc *crtc)
 {
 	return crtc->pipe;
 }

drivers/gpu/drm/imx/imx-drm.h

@@ -13,7 +13,7 @@ struct drm_plane;
 struct imx_drm_crtc;
 struct platform_device;
 
-int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
+unsigned int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
 
 struct imx_drm_crtc_helper_funcs {
 	int (*enable_vblank)(struct drm_crtc *crtc);