i2c: Consistently reject unsupported transactions

Many PC SMBus host controller drivers don't properly handle the case
where they are requested to achieve a transaction they do not support.
Update them so that the consistently print a warning message and
return a single error value in this case.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/busses/i2c-sis96x.c b/drivers/i2c/busses/i2c-sis96x.c
index 29757b2..cde8e58 100644
--- a/drivers/i2c/busses/i2c-sis96x.c
+++ b/drivers/i2c/busses/i2c-sis96x.c
@@ -201,14 +201,8 @@
 			SIS96x_PROC_CALL : SIS96x_WORD_DATA);
 		break;
 
-	case I2C_SMBUS_BLOCK_DATA:
-		/* TO DO: */
-		dev_info(&adap->dev, "SMBus block not implemented!\n");
-		return -EOPNOTSUPP;
-		break;
-
 	default:
-		dev_info(&adap->dev, "Unsupported SMBus operation\n");
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
 		return -EOPNOTSUPP;
 	}