platform/x86: silicom-platform: clean up a check

The error message in this code can't be reached because value is either
zero or non-zero.  There isn't a third option.  Really, it's nicer to
write this as a one liner.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/a58bffb7-0a8b-4195-b273-f65a188ace7b@moroto.mountain


Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>