fs/timerfd.c: make use of wait_event_interruptible_locked_irq()

This patch modifies the fs/timerfd.c to use the newly created
wait_event_interruptible_locked_irq() macro.  This replaces an open
code implementation with a single macro call.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>