drm/i915/fb: drop unused but set variable cpp

Prepare for re-enabling -Wunused-but-set-variable.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ce7a5cb06c562a3399206c521a24f5091a3e7c23.1685119007.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_fb.c

@@ -1601,7 +1601,7 @@ int intel_fill_fb_info(struct drm_i915_private *i915, struct intel_framebuffer *
 	for (i = 0; i < num_planes; i++) {
 		struct fb_plane_view_dims view_dims;
 		unsigned int width, height;
-		unsigned int cpp, size;
+		unsigned int size;
 		u32 offset;
 		int x, y;
 		int ret;
@@ -1618,7 +1618,6 @@ int intel_fill_fb_info(struct drm_i915_private *i915, struct intel_framebuffer *
 				return -EINVAL;
 		}
 
-		cpp = fb->base.format->cpp[i];
 		intel_fb_plane_dims(fb, i, &width, &height);
 
 		ret = convert_plane_offset_to_xy(fb, i, width, &x, &y);