dmaengine: zynqmp_dma: Typecast with enum to fix the coverity warning

Typecast the flags variable with (enum dma_ctrl_flags) in
zynqmp_dma_prep_memcpy function to fix the coverity warning.

Addresses-Coverity: Event mixed_enum_type.
Signed-off-by: Shravya Kumbham <shravya.kumbham@xilinx.com>
Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://lore.kernel.org/r/1653378553-28548-1-git-send-email-radhey.shyam.pandey@amd.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>