misc: replace remaining loff_t with ext2_loff_t

misc: replace remaining loff_t with ext2_loff_t

Replace the remaining loff_t uses with ext2_loff_t, as
was done in patch 1df6a4555, since loff_t is a GCC'ism
and is not portable.

Change-Id: I92e3643c05021a18f40a9a022bbf7e54121e453a
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40951
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@whamcloud.com>