i2c-mv64xxx: Reinitialize hw and driver on I2C bus hang

Under certain conditions, the mv64xxx I2C bus can hang preventing
further operation.  To make the driver more robust, we now reset
the I2C hardware and the driver state machine when such hangs are
detected.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Acked-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>