drm: Make drivers depends on DRM_DW_HDMI

drm: Make drivers depends on DRM_DW_HDMI

DRM_DW_HDMI has a number of dependencies that might not be enabled.
However, drivers were used to selecting it while not enforcing the
DRM_DW_HDMI dependencies.

This could result in Kconfig warnings (and further build breakages) such
as:

  Kconfig warnings: (for reference only)
     WARNING: unmet direct dependencies detected for DRM_DW_HDMI
     Depends on [n]: HAS_IOMEM [=y] && DRM [=m] && DRM_BRIDGE [=y] && DRM_DISPLAY_HELPER [=n]
     Selected by [m]:
     - DRM_SUN8I_DW_HDMI [=m] && HAS_IOMEM [=y] && DRM_SUN4I [=m]

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403262127.kZkttfNz-lkp@intel.com/
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20240327-kms-kconfig-helpers-v3-7-eafee11b84b3@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>