block: Move bdev_unhash_inode() after invalidate_partition()

Move bdev_unhash_inode() after invalidate_partition() as
invalidate_partition() looks up bdev and it cannot find the right bdev
inode after bdev_unhash_inode() is called. Thus invalidate_partition()
would not invalidate page cache of the previously used bdev. Also use
part_devt() when calling bdev_unhash_inode() instead of manually
creating the device number.

Change-Id: Ieda217d808e35b2d3d0a689e027b2022d6077943
Tested-by: Lekshmi Pillai <lekshmicpillai@in.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Git-commit: 4b8c861a7c79806fb9ee564c87f517dc26fc2d1e
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git


[riteshh@codeaurora.org: Resolved merge conflicts]
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>