This patch updates the GPMC's DT DMA property to reflect the updated eDMA
bindings.

Fixes: cce1ee00 ("ARM: DTS: am437x: Use the new DT bindings for the eDMA3")
Signed-off-by: NFranklin S Cooper Jr <fcooper@ti.com>
Acked-by: NRoger Quadros <rogerq@ti.com>
Acked-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>