drm/msm/dp: displayPort driver need algorithm rational

Let's select RATIONAL with dp driver. avoid like:

[...]
x86_64-linux-gnu-ld: drivers/gpu/drm/msm/dp/dp_catalog.o: in function `dp_catalog_ctrl_config_msa':
dp_catalog.c:(.text+0x57e): undefined reference to `rational_best_approximation'

Fixes: c943b49 ("drm/msm/dp: add displayPort driver support")
Reported-by: kernelbot <kernel-bot@kylinos.cn>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Link: https://lore.kernel.org/r/20211110070950.3355597-2-liu.yun@linux.dev
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/Kconfig

@@ -65,6 +65,7 @@ config DRM_MSM_HDMI_HDCP
 config DRM_MSM_DP
 	bool "Enable DisplayPort support in MSM DRM driver"
 	depends on DRM_MSM
+	select RATIONAL
 	default y
 	help
 	  Compile in support for DP driver in MSM DRM driver. DP external