i2c: s3c2410: Print errno code in error logs

The driver not always prints the error code in case of a failure but this
information can be very useful for debugging. So let's print if available.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>