[PATCH] x86_64: Don't do syscall exit tracing twice

int_ret_from_syscall already does syscall exit tracing, so
no need to do it again in the caller.

This caused problems for UML and some other special programs doing
syscall interception.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>