mb/google/geralt: Add NOR-Flash support

Initialize NOR-Flash in the bootblock.

TEST=read nor flash data successfully.
BUG=b:233720142

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: I8ee24b5b24643bce57eb29682d6d0234a6fe8641
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65622
Reviewed-by: Yidi Lin <yidilin@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/geralt/Kconfig

@@ -25,4 +25,8 @@ config MAINBOARD_DIR
 config MAINBOARD_PART_NUMBER
 	string
 	default "Geralt" if BOARD_GOOGLE_GERALT
+
+config BOOT_DEVICE_SPI_FLASH_BUS
+	int
+	default 7
 endif

src/mainboard/google/geralt/bootblock.c

@@ -2,8 +2,9 @@
 
 #include <bootblock_common.h>
 #include <device/mmio.h>
+#include <soc/spi.h>
 
 void bootblock_mainboard_init(void)
 {
-	/* TODO: add mainboard init for bootblock */
+	mtk_snfc_init();
 }