drm/exynos: fixed exynos_drm_gem_map_pages bug.

this patch fixes the problem that the physical memory region to be mapped
to user space could be exceeded. if page fault address was placed at between
buffer start and end then memory region to be mapped would be exceeded.
Signed-off-by: NInki Dae <inki.dae@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -149,22 +149,12 @@ static int exynos_drm_gem_map_pages(struct drm_gem_object *obj,
 	unsigned long pfn;
 
 	if (exynos_gem_obj->flags & EXYNOS_BO_NONCONTIG) {
-		unsigned long usize = buf->size;
-
 		if (!buf->pages)
 			return -EINTR;
 
-		while (usize > 0) {
-			pfn = page_to_pfn(buf->pages[page_offset++]);
-			vm_insert_mixed(vma, f_vaddr, pfn);
-			f_vaddr += PAGE_SIZE;
-			usize -= PAGE_SIZE;
-		}
-
-		return 0;
-	}
-
-	pfn = (buf->dma_addr >> PAGE_SHIFT) + page_offset;
+		pfn = page_to_pfn(buf->pages[page_offset++]);
+	} else
+		pfn = (buf->dma_addr >> PAGE_SHIFT) + page_offset;
 
 	return vm_insert_mixed(vma, f_vaddr, pfn);
 }