mdss: dsi_v2: remove second call to msm_dsi_cmd_dma_tx

There should only be one call to msm_dsi_cmd_dma_tx.

Change-Id: I5af937d029c6eabdda406f69d12f06f68354078c
Signed-off-by: Terence Hampson <thampson@codeaurora.org>