drm/hisilicon/hibmc: select CONFIG_DRM_DISPLAY_DP_HELPER

Without the DP helper code, the newly added displayport support
causes a link failure:

x86_64-linux-ld: drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.o: in function `hibmc_dp_aux_init':
dp_aux.c:(.text+0x37e): undefined reference to `drm_dp_aux_init'
x86_64-linux-ld: drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.o: in function `hibmc_dp_link_set_pattern':
dp_link.c:(.text+0xae): undefined reference to `drm_dp_dpcd_write'
x86_64-linux-ld: drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.o: in function `hibmc_dp_link_get_adjust_train':
dp_link.c:(.text+0x121): undefined reference to `drm_dp_get_adjust_request_voltage'
x86_64-linux-ld: dp_link.c:(.text+0x12e): undefined reference to `drm_dp_get_adjust_request_pre_emphasis'
x86_64-linux-ld: drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.o: in function `hibmc_dp_link_training':
dp_link.c:(.text+0x2b0): undefined reference to `drm_dp_dpcd_write'
x86_64-linux-ld: dp_link.c:(.text+0x2e3): undefined reference to `drm_dp_dpcd_write'

Add both DRM_DISPLAY_DP_HELPER and DRM_DISPLAY_HELPER, which is
in turn required by the former.

Fixes: 0ab6ea2 ("drm/hisilicon/hibmc: add dp module in hibmc")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250127071059.617567-1-arnd@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/hisilicon/hibmc/Kconfig

@@ -4,6 +4,8 @@ config DRM_HISI_HIBMC
 	depends on DRM && PCI
 	depends on MMU
 	select DRM_CLIENT_SELECTION
+	select DRM_DISPLAY_HELPER
+	select DRM_DISPLAY_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_VRAM_HELPER
 	select DRM_TTM