ARM: dts: msm: Add GPI DMA device tree nodes for sdm640

Add GPI device tree nodes for GPI DMA driver. The driver
provides DMA capabilities for peripheral buses such as
I2C, UART, and SPI.

Change-Id: Id1c67bd0755d6d2659616463bf49aa2bdcd6a13a
Signed-off-by: Jishnu Prakash <jprakash@codeaurora.org>