UPSTREAM: x86/syscalls: Refactor syscalltbl.sh

This splits out the code to emit a syscall line.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1bfcbba991f5cfaa9291ff950a593daa972a205f.1454022279.git.luto@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit fba324744bfd2a7948a7710d7a021d76dafb9b67)

Bug: 119769499
Change-Id: Ie36f49882c4c3a69d87288795e4525353bb05ec5
Signed-off-by: Greg Hackmann <ghackmann@google.com>