nohz: Fix !HIGH_RES_TIMERS hang

Simon Horman reported this crash on a system with
high-res timers disabled but nohz enabled:

  > ------------[ cut here ]------------
  > kernel BUG at kernel/irq_work.c:135!

    BUG_ON(!irqs_disabled());

So something enabled interrupts in the periodic tick handling machinery,
and that code path indeed has a local_irq_disable()/enable pair in
tick_nohz_switch_to_nohz() which causes havoc. Fix it.

This patch also fixes a +nohz -hrtimers hang reported by Ingo Molnar.

Change-Id: If3d528d940b20bca12c8d2b15bcef9774605fa00
Reported-by: Simon Horman <horms@verge.net.au>
Reported-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505071425520.4225@nanos


Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-commit: 6b442bc81337913eb775965a67ffdb8a36935422
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git


[salvares@codeaurora.org: resolved context conflicts in tick-sched.c]
Signed-off-by: Sanrio Alvares <salvares@codeaurora.org>