hrtimer: Simplify get_target_base() by returning current base

Instead of fetching again the current cpu base, just take it from the
parameter.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1439907509-9553-2-git-send-email-fweisbec@gmail.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>