spi/sc18is602: Return -EINVAL for probe failures due to I2C function mismatch

If the I2C bus master driver does not support the required functionality,
the driver returns -ENODEV. This causes a silent probe failure without error
message. Since the device has to be explicitly instantiated, and the user
should know the correct bus, this event really reflects an error condition.
Replace error return value with -EINVAL to trigger an error message showing
that the probe function failed.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>