ARM: DTS: da850: Enable DMA for SPI1

Add the needed bindings so the SPI driver can use DMA with SPI1.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Sushaanth Srirangapathi <sushaanth.s@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>