drm/client: convert to drm device based logging

Prefer drm_dbg_kms() and drm_err() over DRM_DEV_DEBUG_KMS() and
DRM_DEV_ERROR().

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191210123050.8799-2-jani.nikula@intel.com