staging: bcm2048: add SPDX License Identifier

Add missing SPDX License Identifier. Reported by checkpatch.
Signed-off-by: Ioannis Valasakis <code@wizofe.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/media/bcm2048/radio-bcm2048.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * drivers/staging/media/radio-bcm2048.c
  *

drivers/staging/media/bcm2048/radio-bcm2048.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * drivers/staging/media/radio-bcm2048.h
  *