fscache: Use only one fscache_object_cong_wait.

This is an update of the original patch, removing put_cpu_var() which
was overseen in the initial patch.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>