LU-8465 e2fsck: fix memory leaks with pfsck enabled

LU-8465 e2fsck: fix memory leaks with pfsck enabled

valgrind detected few memory leaks:

1) quota context is not released after merging.
2) three block bufs are not freed in read_bitmaps_range_start()
3) @refcount_orig should be released

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Change-Id: I13e51c31cacba9ed14bc9f4d4ce82ec0a6cfe610
Reviewed-on: https://review.whamcloud.com/40069
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>