i2c: xiic: Remove the Addressed as slave interrupt

Currently there is no slave mode support in the driver
also in the isr we just ack it and do nothing.
So disable the AAS interrupt.

Signed-off-by: Shubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>