x86, ptrace: Remove set_stopped_child_used_math() in [x]fpregs_set

init_fpu() already ensures that the used_math() is set for the stopped child.
Remove the redundant set_stopped_child_used_math() in [x]fpregs_set()

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100222225240.642169080@sbs-t61.sc.intel.com>
Acked-by: Rolan McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>