bcache: Fixup error handling in register_cache()

bcache: Fixup error handling in register_cache()

Coverity has noticed that the printing of error message in
register_cache() uses already freed bdev_handle to get to bdev. In fact
the problem has been there even before commit "bcache: Convert to
bdev_open_by_path()" just a bit more subtle one - cache object itself
could have been freed by the time we looked at ca->bdev and we don't
hold any reference to bdev either so even that could in principle go
away (due to device unplug or similar). Fix all these problems by
printing the error message before closing the bdev.

Fixes: dc893f51d24a ("bcache: Convert to bdev_open_by_path()")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231004093757.11560-1-jack@suse.cz
Asked-by: Coly Li <colyli@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>