i2c: Drop configure option I2C_DEBUG_CHIP

Now that directory drivers/i2c/chips is gone, configuration option
I2C_DEBUG_CHIP no longer has any effect, so we can drop it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>