drm/display: Make all helpers visible and switch to depends on

All the helpers Kconfig symbols so far have relied on drivers selecting
them, and that's what most drivers did.

However, this creates an issue nowadays when helpers depend on each
other, and select doesn't transitively select a dependency dependencies.

Depends on doesn't have that limitation though, so let's convert those
symbols to be dependable and use depends on between them too.
Suggested-by: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20240327-kms-kconfig-helpers-v3-6-eafee11b84b3@kernel.orgSigned-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/display/Kconfig

 # SPDX-License-Identifier: MIT
 
 config DRM_DISPLAY_HELPER
-	tristate
+	tristate "DRM Display Helpers"
 	depends on DRM
 	help
 	  DRM helpers for display adapters.
 
 config DRM_DISPLAY_DP_AUX_BUS
-	tristate
+	tristate "DRM DisplayPort AUX bus support"
 	depends on DRM
 	depends on OF || COMPILE_TEST
 
 config DRM_DISPLAY_DP_AUX_CEC
 	bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
-	depends on DRM && DRM_DISPLAY_HELPER
-	select DRM_DISPLAY_DP_HELPER
+	depends on DRM
+	depends on DRM_DISPLAY_HELPER
+	depends on DRM_DISPLAY_DP_HELPER
 	select CEC_CORE
 	help
 	  Choose this option if you want to enable HDMI CEC support for
@@ -24,23 +25,24 @@ config DRM_DISPLAY_DP_AUX_CEC
 	  that do support this they often do not hook up the CEC pin.
 
 config DRM_DISPLAY_DP_AUX_CHARDEV
-	bool "DRM DP AUX Interface"
-	depends on DRM && DRM_DISPLAY_HELPER
-	select DRM_DISPLAY_DP_HELPER
+	bool "DRM DisplayPort AUX Interface"
+	depends on DRM
+	depends on DRM_DISPLAY_HELPER
+	depends on DRM_DISPLAY_DP_HELPER
 	help
 	  Choose this option to enable a /dev/drm_dp_auxN node that allows to
 	  read and write values to arbitrary DPCD registers on the DP aux
 	  channel.
 
 config DRM_DISPLAY_DP_HELPER
-	bool
+	bool "DRM DisplayPort Helpers"
 	depends on DRM_DISPLAY_HELPER
 	help
 	  DRM display helpers for DisplayPort.
 
 config DRM_DISPLAY_DP_TUNNEL
-	bool
-	select DRM_DISPLAY_DP_HELPER
+	bool "DRM DisplayPort tunnels support"
+	depends on DRM_DISPLAY_DP_HELPER
 	help
 	  Enable support for DisplayPort tunnels. This allows drivers to use
 	  DP tunnel features like the Bandwidth Allocation mode to maximize the
@@ -60,13 +62,13 @@ config DRM_DISPLAY_DP_TUNNEL_STATE_DEBUG
 	  If in doubt, say "N".
 
 config DRM_DISPLAY_HDCP_HELPER
-	bool
+	bool "DRM HDCD Helpers"
 	depends on DRM_DISPLAY_HELPER
 	help
 	  DRM display helpers for HDCP.
 
 config DRM_DISPLAY_HDMI_HELPER
-	bool
+	bool "DRM HDMI Helpers"
 	depends on DRM_DISPLAY_HELPER
 	help
 	  DRM display helpers for HDMI.