ARM: dts: stm32: move stmmac axi config in ethernet node on stm32mp15

It fixes the following warning seen running "make dtbs_check W=1"

Warning (simple_bus_reg): /soc/stmmac-axi-config: missing or empty
reg/ranges property
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp151.dtsi

@@ -1416,12 +1416,6 @@ crc1: crc@58009000 {
 			status = "disabled";
 		};
 
-		stmmac_axi_config_0: stmmac-axi-config {
-			snps,wr_osr_lmt = <0x7>;
-			snps,rd_osr_lmt = <0x7>;
-			snps,blen = <0 0 0 0 16 8 4>;
-		};
-
 		ethernet0: ethernet@5800a000 {
 			compatible = "st,stm32mp1-dwmac", "snps,dwmac-4.20a";
 			reg = <0x5800a000 0x2000>;
@@ -1447,6 +1441,12 @@ ethernet0: ethernet@5800a000 {
 			snps,axi-config = <&stmmac_axi_config_0>;
 			snps,tso;
 			status = "disabled";
+
+			stmmac_axi_config_0: stmmac-axi-config {
+				snps,wr_osr_lmt = <0x7>;
+				snps,rd_osr_lmt = <0x7>;
+				snps,blen = <0 0 0 0 16 8 4>;
+			};
 		};
 
 		usbh_ohci: usb@5800c000 {