Revert "drm: add missing dependency to DRM_PANEL_EDP"

This reverts commit d6107f1b.

When this branch is merged with 5.17 release, this commit causes the
following Kconfig error:

drivers/gpu/drm/Kconfig:83:error: recursive dependency detected!
drivers/gpu/drm/Kconfig:83:	symbol DRM_KMS_HELPER is selected by DRM_PANEL_EDP
drivers/gpu/drm/panel/Kconfig:102:	symbol DRM_PANEL_EDP depends on DRM_KMS_HELPER