pfe_ctrl_timer: use timeout_interruptible instead of _uninterruptible.

Based on the way this loop works, there should be no difference in
functionality (it just loops forever anyway, and deliberately exits if the
thread is requested to exit, and only runs handlers if the current time is
past their scheduled time).  But using interruptible waits leaves the thread
in the S state instead of D, so it doesn't incorrectly increase the load

Change-Id: I2b13bea8709604b220befedf58a6cb585b368650
diff --git a/pfe_ctrl/pfe_ctrl.c b/pfe_ctrl/pfe_ctrl.c
index 3af2e61..158fcab 100644
--- a/pfe_ctrl/pfe_ctrl.c
+++ b/pfe_ctrl/pfe_ctrl.c
@@ -486,7 +486,7 @@
 	while (1)
-		schedule_timeout_uninterruptible(ctrl->timer_period);
+		schedule_timeout_interruptible(ctrl->timer_period);