i386: arch/x86/math-emu/fpu_entry.c warning fix

arch/x86/math-emu/fpu_entry.c:555: warning: 'entry_sel_off.empty' is used uninitialized in this function

Presumably it's harmless, but I'll sleep better at night knowing that we
initialised it.

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>