MLK-14393 i2c: imx-lpi2c: directly retrun ISR when detect a NACK

A NACK flag in ISR means i2c bus error. In such codition,
there is no need to do read/write operation. It's better
to return ISR directly and then stop i2c transfer.

Signed-off-by: Gao Pan <pandy.gao@nxp.com>
(cherry-pick from 839d59e48b6fdbd882776a48a88ce26ff14d8b86)
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>