x86: remove STR() macros

This patch removes the __STR() and STR() macros from x86_64 header files.
They seem to be legacy, and has no more users. Even if there were users,
they should use __stringify() instead.

In fact, there were one third place in which this macro was defined
(ia32_binfmt.c), and used just below. In this file, usage was properly
converted to __stringify()

[ tglx: arch/x86 adaptation ]

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>