MLK-20208-3 mxc IPUv3: disp: Avoid division by zero in ipu_init_async_panel()

MLK-20208-3 mxc IPUv3: disp: Avoid division by zero in ipu_init_async_panel()

To avoid potential division by zero in ipu_init_async_panel(),
let's check the di_clk rate prior to that.

Detected by CoverityScan, CID#56264 ("Division or modulo by zero")

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit d7777247e6ba4ca9fcc313bef6672060859fed19)
Signed-off-by: Arulpandiyan Vadivel <arulpandiyan_vadivel@mentor.com>
Signed-off-by: Shrikant Bobade <Shrikant_Bobade@mentor.com>
(cherry picked from commit 739a8482f07187566ec8777dbd2d4b79a1056c49)