i2c: Improve logging on failure to probe for ->class devices

While writing the i2c-imc driver, I noticed that the warning message
when the i2c core can't figure out how to probe is mostly useless.
This trivial patch improves it.

Signed-off-by: Andy Lutomirski <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/i2c-core.c

···
 		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
 				     I2C_SMBUS_BYTE, &dummy);
 	else {
-		dev_warn(&adap->dev, "No suitable probing method supported\n");
+		dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
+			 addr);
 		err = -EOPNOTSUPP;
 	}