timer: Remove pointless return value of do_usleep_range()

timer: Remove pointless return value of do_usleep_range()

The only user ignores it anyway and rightfully so.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.756060258@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>