staging: wfx: fix HIF API license

Apache-2.0 is not allowed in the kernel.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220113085524.1110708-3-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/hif_api_cmd.h

-/* SPDX-License-Identifier: Apache-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only or Apache-2.0 */
 /*
  * WF200 hardware interface definitions
  *

drivers/staging/wfx/hif_api_general.h

-/* SPDX-License-Identifier: Apache-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only or Apache-2.0 */
 /*
  * WF200 hardware interface definitions
  *

drivers/staging/wfx/hif_api_mib.h

-/* SPDX-License-Identifier: Apache-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-only or Apache-2.0 */
 /*
  * WF200 hardware interface definitions
  *