x86, arm: Add missing license tag to syscall tables files

syscall*.tbl files were added to make it easier to check which system
calls are supported on each architecture and to check for their numbers.

Arm and x86 files lack Linux-syscall-note license exception present in
files for all other architectures.
Signed-off-by: Marcin Juszkiewicz <marcin@juszkiewicz.com.pl>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240229145101.553998-1-marcin@juszkiewicz.com.pl

arch/arm/tools/syscall.tbl

+# SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
 #
 # Linux system call numbers and entry vectors
 #

arch/x86/entry/syscalls/syscall_32.tbl

+# SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
 #
 # 32-bit system call numbers and entry vectors
 #

arch/x86/entry/syscalls/syscall_64.tbl

+# SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
 #
 # 64-bit system call numbers and entry vectors
 #