futex: Provide and use pi_state_update_owner()

commit c5cade20 upstream

Updating pi_state::owner is done at several places with the same
code. Provide a function for it and use that at the obvious places.

This is also a preparation for a bug fix to avoid yet another copy of the
same code or alternatively introducing a completely unpenetratable mess of
gotos.

Change-Id: I08631f77e21eb3faacb13fc8a39184a0b6728f24
Originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 0e1501f7
Git-repo: https://android.googlesource.com/kernel/msm


Signed-off-by: PavanKumar S.R. <pavasr@codeaurora.org>