arm: mediatek: add support for MediaTek MT7988 SoC

This patch adds basic support for MediaTek MT7988 SoC.
This includes files that will initialize the SoC after boot and
its device tree.

diff --git a/arch/arm/mach-mediatek/Kconfig b/arch/arm/mach-mediatek/Kconfig
index 04aa2fd..8971e2d 100644
--- a/arch/arm/mach-mediatek/Kconfig
+++ b/arch/arm/mach-mediatek/Kconfig
@@ -58,6 +58,15 @@
 	  including UART, SPI, SPI flash, USB3.0, MMC, NAND, SNFI, PWM, PCIe,
 	  Gigabit Ethernet, I2C, built-in 4x4 Wi-Fi, and PCIe.
 
+config TARGET_MT7988
+	bool "MediaTek MT7988 SoC"
+	select ARM64
+	select CPU
+	help
+	  The MediaTek MT7988 is a ARM64-based SoC with a quad-core Cortex-A73.
+	  including UART, SPI, SPI flash, USB3.0, MMC, NAND, SNFI, PWM, PCIe,
+	  10 Gigabit Ethernet , I2C, and PCIe.
+
 config TARGET_MT8183
 	bool "MediaTek MT8183 SoC"
 	select ARM64
@@ -104,6 +113,7 @@
 	default "mt7629" if TARGET_MT7629
 	default "mt7981" if TARGET_MT7981
 	default "mt7986" if TARGET_MT7986
+	default "mt7988" if TARGET_MT7988
 	default "mt8183" if TARGET_MT8183
 	default "mt8512" if TARGET_MT8512
 	default "mt8516" if TARGET_MT8516
@@ -121,6 +131,7 @@
 	default "mt7629" if TARGET_MT7629
 	default "mt7981" if TARGET_MT7981
 	default "mt7986" if TARGET_MT7986
+	default "mt7988" if TARGET_MT7988
 	default "mt8183" if TARGET_MT8183
 	default "mt8512" if TARGET_MT8512
 	default "mt8516" if TARGET_MT8516
@@ -135,7 +146,7 @@
 	string
 	default "media=nor" if TARGET_MT8518 || TARGET_MT8512 || TARGET_MT7629 || TARGET_MT7622
 	default "media=emmc" if TARGET_MT8516 || TARGET_MT8365 || TARGET_MT8183
-	default "media=snand;nandinfo=2k+64" if TARGET_MT7981 || TARGET_MT7986
+	default "media=snand;nandinfo=2k+64" if TARGET_MT7981 || TARGET_MT7986 || TARGET_MT7988
 	default "lk=1" if TARGET_MT7623
 
 endif