drivers: android: Fix the SPDX comment style

C source files should have `//` as SPDX comment and not `/**/`. Fix this
by running checkpatch on the file.
Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
Link: https://lore.kernel.org/r/20200724131449.zvjutbemg3vqhrzh@mrinalpandeySigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binderfs.c

-/* SPDX-License-Identifier: GPL-2.0 */
+// SPDX-License-Identifier: GPL-2.0
 
 #include <linux/compiler_types.h>
 #include <linux/errno.h>