vfio/fsl-mc: Fix a typo in a message

L and S are swapped in the message.
s/VFIO_FLS_MC/VFIO_FSL_MC/

Also use 'ret' instead of 'WARN_ON(ret)' to avoid a duplicated message.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Diana Craciun <diana.craciun@oss.nxp.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/a7c1394346725b7435792628c8d4c06a0a745e0b.1662134821.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>