x86-64, doc: Remove int 0xcc from entry_64.S documentation

Commit 3ae36655 (x86-64: Rework vsyscall
emulation and add vsyscall= parameter) removed the special use of the
0xcc IDT vector.

Remove it from Documentation/x86/entry_64.txt also.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Acked-by: Andy Lutomirski <luto@MIT.EDU>
Link: http://lkml.kernel.org/r/1313447210-9149-1-git-send-email-cesarb@cesarb.net


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>