drm/rockchip: Fix link error when CONFIG_DRM_ANALOGIX_DP undefined

drm/rockchip: Fix link error when CONFIG_DRM_ANALOGIX_DP undefined

Fixes the following link error when CONFIG_DRM_ANALOGIX_DP is not defined:

ERROR: "analogix_dp_start_crc" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
ERROR: "analogix_dp_stop_crc" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!

Fixes: 3190e58dafaf ("drm/rockchip: Implement CRC debugfs API")
Cc: Tomeu Vizoso <[email protected]>
Cc: Mark Yao <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Heiko Stuebner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Emil Velikov <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>
Signed-off-by: Sean Paul <[email protected]>