ARM: dts: am437x-cm-t43: Correct the dmas property of spi0

The DMA binding for eDMA needs 2 parameters, not 1.
The second, missing parameter is the tptc to be used for the channel.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>