i2c: omap: errata i462: fix incorrect ack for arbitration lost interrupt

The errata handling function acks wrong interrupt in case of "Arbitration
lost". Fix it.

Discovered during code review, the real impact of the bug is unknown.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>