Revert dma: imx-dma: Fix kernel crash due to missing clock conversion

This reverts 9ea2c02bafe276e97b592a046ac733610a6d57fd, which was commit
a2367db2ec5e7fc6fe93e221e0fcdee81b053daf upstream.

It broke the build on 3.4, and was not needed there.

Reported-by: Eric Bénard <eric@eukrea.com>
Cc: Javier Martin <javier.martin@vista-silicon.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>