treewide: Migrate CONFIG_BOARD_EARLY_INIT_R to Kconfig

Migrate the CONFIG_BOARD_EARLY_INIT_R option to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/B4420QDS_NAND_defconfig b/configs/B4420QDS_NAND_defconfig
index d5c57a4..e12c8ea 100644
--- a/configs/B4420QDS_NAND_defconfig
+++ b/configs/B4420QDS_NAND_defconfig
@@ -15,6 +15,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="RAMBOOT_PBL,SPL_FSL_PBL"
 CONFIG_BOOTDELAY=10
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
+CONFIG_BOARD_EARLY_INIT_R=y
 # CONFIG_SPL_FRAMEWORK is not set
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_I2C_SUPPORT=y