drm/exynos: use %pad for dma_addr_t

Use %pad for dma_addr_t, because a dma_addr_t type can vary
based on build options. So, it prevents possible build warnings
in printks.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>