[PATCH -next] drm/bridge: it6505: Fix build error

[YueHaibing]

If DRM_ITE_IT6505 is y but DRM_DP_HELPER is m, building failed:

drivers/gpu/drm/bridge/ite-it6505.o: In function `it6505_i2c_remove':
ite-it6505.c:(.text+0x35c): undefined reference to `drm_dp_aux_unregister'
drivers/gpu/drm/bridge/ite-it6505.o: In function `it6505_dpcd_read':
ite-it6505.c:(.text+0x420): undefined reference to `drm_dp_dpcd_read'
drivers/gpu/drm/bridge/ite-it6505.o: In function `it6505_get_dpcd':
ite-it6505.c:(.text+0x4a4): undefined reference to `drm_dp_dpcd_read'
drivers/gpu/drm/bridge/ite-it6505.o: In function `it6505_dpcd_write':
ite-it6505.c:(.text+0x52c): undefined reference to `drm_dp_dpcd_write'

Select DRM_DP_HELPER for DRM_ITE_IT6505 to fix this.

Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
Signed-off-by: YueHaibing <yuehaibing at huawei.com>
---
 drivers/gpu/drm/bridge/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index c86f5be4dfe0..1b8721a7a6df 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -78,6 +78,7 @@ config DRM_DISPLAY_CONNECTOR
 config DRM_ITE_IT6505
         tristate "ITE IT6505 DisplayPort bridge"
         depends on OF
+	select DRM_DP_HELPER
         select DRM_KMS_HELPER
         select EXTCON
         help
-- 
2.17.1