ARM: dts: msm: Configure IPA rx polling parameters for 8940

Make a change to configure the IPA rx polling timeout and
polling iteration count for 8940.

Change-Id: I36bcb67d27aec6a0cb43a60d3675d067eb6788a6
Acked-by: Mohammed Javid <mjavid@qti.qualcomm.com>
Signed-off-by: Utkarsh Saxena <usaxena@codeaurora.org>