spi: spi-topcliff-pch: Remove some dead code

Since commit 0d357739

 ("spi: spi-topcliff-pch: Remove deprecated
create_singlethread_workqueue"), 'retval' is no more used in this function.

So some now dead code can be removed.
Also axe a debug message which looks useless now.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>