ARM: dts: aspeed: Rename flash-controller nodes

The device tree compiler has started spitting out warnings about these
names, insisting they be called 'spi':

 ../arch/arm/boot/dts/aspeed-g5.dtsi:108.35-128.5: Warning
 (spi_bus_bridge): /ahb/flash-controller@1e631000: node name for SPI
 buses should be 'spi'
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>

arch/arm/boot/dts/aspeed-g4.dtsi

@@ -53,7 +53,7 @@ ahb {
 		#size-cells = <1>;
 		ranges;
 
-		fmc: flash-controller@1e620000 {
+		fmc: spi@1e620000 {
 			reg = < 0x1e620000 0x94
 				0x20000000 0x10000000 >;
 			#address-cells = <1>;
@@ -69,7 +69,7 @@ flash@0 {
 			};
 		};
 
-		spi: flash-controller@1e630000 {
+		spi: spi@1e630000 {
 			reg = < 0x1e630000 0x18
 				0x30000000 0x10000000 >;
 			#address-cells = <1>;

arch/arm/boot/dts/aspeed-g5.dtsi

@@ -60,7 +60,7 @@ ahb {
 		#size-cells = <1>;
 		ranges;
 
-		fmc: flash-controller@1e620000 {
+		fmc: spi@1e620000 {
 			reg = < 0x1e620000 0xc4
 				0x20000000 0x10000000 >;
 			#address-cells = <1>;
@@ -86,7 +86,7 @@ flash@2 {
 			};
 		};
 
-		spi1: flash-controller@1e630000 {
+		spi1: spi@1e630000 {
 			reg = < 0x1e630000 0xc4
 				0x30000000 0x08000000 >;
 			#address-cells = <1>;
@@ -106,7 +106,7 @@ flash@1 {
 			};
 		};
 
-		spi2: flash-controller@1e631000 {
+		spi2: spi@1e631000 {
 			reg = < 0x1e631000 0xc4
 				0x38000000 0x08000000 >;
 			#address-cells = <1>;