Low priority thread holding the i2c bus mutex could block higher
priority threads to access the bus resulting in unacceptable
latencies. Change the mutex type to rt_mutex preventing priority
inversion.
Tested-by: NPeter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@nokia.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>