treewide: Add SPDX license identifier - Kbuild

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

      GPL-2.0

Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/parisc/include/asm/Kbuild

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 generated-y += syscall_table_32.h
 generated-y += syscall_table_64.h
 generated-y += syscall_table_c32.h

arch/parisc/include/uapi/asm/Kbuild

@@ -1,2 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
 generated-y += unistd_32.h
 generated-y += unistd_64.h