PM: hibernate: fix sparse warnings

When building the kernel with sparse enabled 'C=1' the following
warnings shows up:

kernel/power/swap.c:390:29: warning: incorrect type in assignment (different base types)
kernel/power/swap.c:390:29:    expected int ret
kernel/power/swap.c:390:29:    got restricted blk_status_t

This is due to function hib_wait_io() returns a 'blk_status_t' which is
a bitwise u8. Commit 5416da01 ("PM: hibernate: Remove
blk_status_to_errno in hib_wait_io") seemed to have mixed up the return
type. However, the 4e4cbee9 ("block: switch bios to blk_status_t")
actually broke the behaviour by returning the wrong type.

Rework so function hib_wait_io() returns a 'int' instead of
'blk_status_t' and make sure to call function
blk_status_to_errno(hb->error)' when returning from function
hib_wait_io() a int gets returned.

Fixes: 4e4cbee9 ("block: switch bios to blk_status_t")
Fixes: 5416da01 ("PM: hibernate: Remove blk_status_to_errno in hib_wait_io")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/swap.c

@@ -299,14 +299,14 @@ static int hib_submit_io(int op, int op_flags, pgoff_t page_off, void *addr,
 	return error;
 }
 
-static blk_status_t hib_wait_io(struct hib_bio_batch *hb)
+static int hib_wait_io(struct hib_bio_batch *hb)
 {
 	/*
 	 * We are relying on the behavior of blk_plug that a thread with
 	 * a plug will flush the plug list before sleeping.
 	 */
 	wait_event(hb->wait, atomic_read(&hb->count) == 0);
-	return hb->error;
+	return blk_status_to_errno(hb->error);
 }
 
 /*