drm/connector: Make drm_connector_attach_hdr_output_metadata_property() return void

drm/connector: Make drm_connector_attach_hdr_output_metadata_property() return void

drm_connector_attach_hdr_output_metadata_property() always returns zero,
since drm_object_attach_property() returns void. No caller checks the
return value, so change the return type to void.

Also fix a typo in the kerneldoc ("HDR_OUTPUT_METADA" -> "HDR_OUTPUT_METADATA").

Reviewed-by: Melissa Wen <mwen@igalia.com>
Link: https://patch.msgid.link/20260330133446.3265938-2-mcanal@igalia.com
Signed-off-by: Maíra Canal <mcanal@igalia.com>