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>