arm64: dts: mediatek: mt7988: correct sram size of eth

Original memory size for eth has overlap the region for eip197.
Without this patch, inside-secure driver for eip197 will fail at
devm_ioremap_resource. It's because ethernet driver request same memory
region first.
Correct the memory size for ethernet in this patch.

Signed-off-by: Chris Chou <chris.chou at mediatek.com>

Author: Chris Chou

arch/arm64/boot/dts/mediatek/mt7988a.dtsi

@@ -961,7 +961,7 @@
 		eth: ethernet@15100000 {
 			compatible = "mediatek,mt7988-eth";
 			reg = <0 0x15100000 0 0x80000>,
-			      <0 0x15400000 0 0x380000>;
+			      <0 0x15400000 0 0x200000>;
 			interrupts = <GIC_SPI 196 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 197 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 198 IRQ_TYPE_LEVEL_HIGH>,