arm64: zynqmp: Add u-boot,dm-pre-reloc to dpsub node

u-boot,dm-pre-reloc is necessary for DP driver to allocate enough space for
framebuffer before relocation.
Power domain driver is called when video console is used for example by
loading BMP image.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/5e93acee1746913a6e42741e5e797f0b4ab98d44.1637239230.git.michal.simek@xilinx.com
diff --git a/arch/arm/dts/zynqmp.dtsi b/arch/arm/dts/zynqmp.dtsi
index 1332f53..07d4d4b 100644
--- a/arch/arm/dts/zynqmp.dtsi
+++ b/arch/arm/dts/zynqmp.dtsi
@@ -961,6 +961,7 @@
 		};
 
 		zynqmp_dpsub: display@fd4a0000 {
+			u-boot,dm-pre-reloc;
 			compatible = "xlnx,zynqmp-dpsub-1.7";
 			status = "disabled";
 			reg = <0x0 0xfd4a0000 0x0 0x1000>,