spi/omap2-mcpsi: Always call spi_finalize_current_message()

The spi queue waits forever for spi_finalize_current_message() to be
called, blocking the bus.  Ensure that all error paths from
omap2_mcspi_transfer_one_message() call spi_finalize_current_message().

Signed-off-by: Fionn Cleary <fionn.cleary@streamunlimited.com>
Signed-off-by: Mark Brown <broonie@kernel.org>