drm/i915: fix open-coded DIV_ROUND_UP

Use the nice Kernel macro, it makes the code much more readable.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -261,7 +261,7 @@ i915_gem_dumb_create(struct drm_file *file,
 		     struct drm_mode_create_dumb *args)
 {
 	/* have to work out size/pitch and return them */
-	args->pitch = ALIGN(args->width * ((args->bpp + 7) / 8), 64);
+	args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
 	args->size = args->pitch * args->height;
 	return i915_gem_create(file, dev,
 			       args->size, &args->handle);