drm/rockchip: Don't build rockchip_drm_vop as modules

rockchip_drm_vop's module init had moved to rockchip_vop_reg.c
so no need to build rockchip_drm_vop.ko
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>

drivers/gpu/drm/rockchip/Makefile

@@ -3,10 +3,9 @@
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
 rockchipdrm-y := rockchip_drm_drv.o rockchip_drm_fb.o rockchip_drm_fbdev.o \
-		rockchip_drm_gem.o
+		rockchip_drm_gem.o rockchip_drm_vop.o
 
 obj-$(CONFIG_ROCKCHIP_DW_HDMI) += dw_hdmi-rockchip.o
 obj-$(CONFIG_ROCKCHIP_DW_MIPI_DSI) += dw-mipi-dsi.o
 
-obj-$(CONFIG_DRM_ROCKCHIP) += rockchipdrm.o rockchip_drm_vop.o \
-				rockchip_vop_reg.o
+obj-$(CONFIG_DRM_ROCKCHIP) += rockchipdrm.o rockchip_vop_reg.o