i2c: iproc: handle invalid slave state

Add the code to handle an invalid state when both bits S_RX_EVENT
(indicating a transaction) and S_START_BUSY (indicating the end
of transaction - transition of START_BUSY from 1 to 0) are set in
the interrupt status register during a slave read.

Signed-off-by: Roman Bacik <roman.bacik@broadcom.com>
Fixes: 1ca1b451 ("i2c: iproc: handle Master aborted error")
Acked-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>