drm/rockchip: fix compile warnings for 64-bit

Rockchip DRM does not yet build properly for ARM64, but we might as well
get the printf formatting correct now, to avoid the following warnings:

drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c: In function 'rockchip_drm_fbdev_create':
drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c:111:2: warning: format '%d' expects argument of type 'int', but argument 8 has type 'size_t' [-Wformat=]
  DRM_DEBUG_KMS("FB [%dx%d]-%d kvaddr=%p offset=%ld size=%d\n",
  ^

drivers/gpu/drm/rockchip/rockchip_drm_gem.c: In function 'rockchip_gem_alloc_buf':
drivers/gpu/drm/rockchip/rockchip_drm_gem.c:41:3: warning: format '%x' expects argument of type 'unsigned int', but argument 2 has type 'size_t' [-Wformat=]
   DRM_ERROR("failed to allocate %#x byte dma buffer", obj->size);
   ^

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1465494392-92489-1-git-send-email-briannorris@chromium.org