drm/cma: Fix compile fail due to fomat->format typo

Apparently my arm .config had reverted to CMA=n at some point, so I
failed to notice that I typoed the code. Fix it up so that the
cma helper will compile again.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Fixes: ca984a99 ("drm/fb_cma_helper: Replace drm_format_info() with fb->format")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161215142927.20761-1-ville.syrjala@linux.intel.comReviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/gpu/drm/drm_fb_cma_helper.c

@@ -309,7 +309,7 @@ static void drm_fb_cma_describe(struct drm_framebuffer *fb, struct seq_file *m)
 	seq_printf(m, "fb: %dx%d@%4.4s\n", fb->width, fb->height,
 			(char *)&fb->format->format);
 
-	for (i = 0; i < fb->fomat->num_planes; i++) {
+	for (i = 0; i < fb->format->num_planes; i++) {
 		seq_printf(m, "   %d: offset=%d pitch=%d, obj: ",
 				i, fb->offsets[i], fb->pitches[i]);
 		drm_gem_cma_describe(fb_cma->obj[i], m);