iommu/vt-d: Fix an unbalanced rcu_read_lock/rcu_read_unlock()

iommu/vt-d: Fix an unbalanced rcu_read_lock/rcu_read_unlock()

commit 4e5973dd2725bb30c3db622f7d73f7a5864ce718 upstream.

If we return -EOPNOTSUPP, the rcu lock remains lock. This is spurious.
Go through the end of the function instead. This way, the missing
'rcu_read_unlock()' is called.

Fixes: 7afd7f6aa21a ("iommu/vt-d: Check FL and SL capability sanity in scalable mode")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/40cc077ca5f543614eab2a10e84d29dd190273f6.1636217517.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20211126135556.397932-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>