Call vn_close on the backing file vnode if ufs_extattr_enable failed to avoid leaking it.
Call vn_close on the backing file vnode if ufs_extattr_enable failed to
avoid leaking it.

Reviewed by:	rwatson

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase