drm/exynos: gem: Fix sparse warning

kvaddr element of the exynos_gem object points to a memory buffer, thus
it should not have a __iomem annotation. Then, to avoid a warning or
casting on assignment to fbi structure, the screen_buffer element of the
union should be used instead of the screen_base.
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -92,7 +92,7 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper *helper,
 	offset = fbi->var.xoffset * fb->format->cpp[0];
 	offset += fbi->var.yoffset * fb->pitches[0];
 
-	fbi->screen_base = exynos_gem->kvaddr + offset;
+	fbi->screen_buffer = exynos_gem->kvaddr + offset;
 	fbi->screen_size = size;
 	fbi->fix.smem_len = size;
 

drivers/gpu/drm/exynos/exynos_drm_gem.h

@@ -40,7 +40,7 @@ struct exynos_drm_gem {
 	unsigned int		flags;
 	unsigned long		size;
 	void			*cookie;
-	void __iomem		*kvaddr;
+	void			*kvaddr;
 	dma_addr_t		dma_addr;
 	unsigned long		dma_attrs;
 	struct sg_table		*sgt;