drm/rockchip: vop: move line_flag_num to interrupt registers

In the hardware design process, the design of line flags
register is associated with the interrupt register,
placing the line flags in the interrupt definition is
more reasonable, and it would make multi-vop define easilier.

Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/1501049960-6006-1-git-send-email-mark.yao@rock-chips.com