msm: mdss: Ignore overflow errors in dma_tpg_tx path

Ignore DSI FIFO overflow errors while sending DCS
commands in dma_tpg_tx path. This extends the handling
of overflow as done in non-TPG path through commit
2aa61921 "msm: mdss:
ignore overflow error when sending dcs command" to
the dma_tpg path.

Change-Id: I9ab9b79d7c2100cf9f2e7c01983500c098a12770
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>