jfs: Remove unnecessary code in jfs_get_acl

The get_acl inode operation is called only when no ACL is cached.  It
makes no sense to check for a cached ACL as the first thing inside such
inode operations.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>