kernel: i2c-pxa: remove slave

kernel: i2c-pxa: remove slave

Removing i2c pxa slave

The i2c-pxa is typically not use in slave mode. It does not make sense
to have slave mode enabled by default.
Having slave mode enabled prevents the i2c controller from being reset
if a real slave device such as an SFP is attached to the i2c-pxa bus and
locks it up.
Disable slave mode so that the i2c controller can be reset if the bus is
locked up.
If someone actually has a need for pxa slave mode this can be enabled in
kernel config.

Signed-off-by: Scott Roberts <ttocsr@gmail.com>