drm/rockchip: add missing header dependencies

drm/rockchip: add missing header dependencies

We get 2 warnings when building kernel with W=1:
drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c:130:5: warning: no previous prototype for 'rockchip_drm_fbdev_init' [-Wmissing-prototypes]
drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c:173:6: warning: no previous prototype for 'rockchip_drm_fbdev_fini' [-Wmissing-prototypes]

In fact, these functions are declared
in drivers/gpu/drm/rockchip/rockchip_drm_fbdev.h,
so this patch adds missing header dependencies.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1474789109-22010-1-git-send-email-baoyou.xie@linaro.org