ck_fifo: Add ck_fifo_*_deinit routines.

These allow for reclamation of garbage node in an empty FIFO.
Based on patch submitted by Rajesh R <rr01803@gm....>.

include/ck_fifo.h

@@ -111,6 +111,15 @@ ck_fifo_spsc_init(struct ck_fifo_spsc *fifo, struct ck_fifo_spsc_entry *stub)
 	return;
 }
 
+CK_CC_INLINE static void
+ck_fifo_spsc_deinit(struct ck_fifo_spsc *fifo, struct ck_fifo_spsc_entry **garbage)
+{
+
+	*garbage = fifo->garbage;
+	fifo->head = fifo->tail = NULL;
+	return;
+}
+
 CK_CC_INLINE static void
 ck_fifo_spsc_enqueue(struct ck_fifo_spsc *fifo,
 		     struct ck_fifo_spsc_entry *entry,
@@ -223,6 +232,15 @@ ck_fifo_mpmc_init(struct ck_fifo_mpmc *fifo, struct ck_fifo_mpmc_entry *stub)
 	return;
 }
 
+CK_CC_INLINE static void
+ck_fifo_mpmc_deinit(struct ck_fifo_mpmc *fifo, struct ck_fifo_mpmc_entry **garbage)
+{
+
+	*garbage = fifo->head.pointer;
+	fifo->head.pointer = fifo->tail.pointer = NULL;
+	return;
+}
+
 CK_CC_INLINE static void
 ck_fifo_mpmc_enqueue(struct ck_fifo_mpmc *fifo,
 		     struct ck_fifo_mpmc_entry *entry,