dmaengine: zynqmp_dma: Remove max len check in zynqmp_dma_prep_memcpy

Remove check for "len > ZYNQMP_DMA_MAX_TRANS_LEN" as its not needed.
If the length is larger, the transfer is split up into multiple parts
with the max descriptor length already.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Kedareswara rao Appana <appanad@xilinx.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>