x86: Remove dead hlt_use_halt code

x86: Remove dead hlt_use_halt code

The hlt_use_halt function returns always true and there is only
one definition of it.

The default_idle function can then get ride of the if ...
statement and we can remove the else branch.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linaro-dev@lists.linaro.org
Cc: patches@linaro.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1351181591-8710-1-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>