spi: fsi: Fix transfer returning without finalizing message

In the case that the SPI mux isn't set, the transfer_one_message
function returns without finalizing the message. This means that
the transfer never completes, resulting in hung tasks and an
eventual kernel panic. Fix it by finalizing the transfer in this
case.

Fixes: 9211a441

 ("spi: fsi: Check mux status before transfers")
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20201110214736.25718-1-eajames@linux.ibm.com
Signed-off-by: Mark Brown <broonie@kernel.org>