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.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>