i2c: imx: Fix reinit_completion() use

Make sure to call reinit_completion() before dma is started to avoid race
condition where reinit_completion() is called after complete() and before
wait_for_completion_timeout().

Signed-off-by: Esben Haabendal <eha@deif.com>
Fixes: ce1a7884 ("i2c: imx: add DMA support for freescale i2c driver")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org