x86: remove TRAP_FLAG

This gets rid of the local constant macro TRAP_FLAG.
It's redundant with the public constant macro X86_EFLAGS_TF.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>