ARM: dts: msm: Add GSI channels for SPI serial engines on SDM670

Add the DMA channel definitions for all SPI serial engines.
SPI controller will choose GSI DMA as the default data transfer method
and fall back to SW IO mode (FIFO mode) only if dma channel definitions
are removed from the device tree.

Change-Id: Ifdc0a71473c219121c587450c9d6632534ea99d9
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>