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/P1021RDB-PC_SDCARD_defconfig b/configs/P1021RDB-PC_SDCARD_defconfig
index 8075141..6ce9e2f 100644
--- a/configs/P1021RDB-PC_SDCARD_defconfig
+++ b/configs/P1021RDB-PC_SDCARD_defconfig
@@ -15,6 +15,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="SDCARD"
 CONFIG_BOOTDELAY=10
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_BOARD_EARLY_INIT_R=y
 # CONFIG_SPL_FRAMEWORK is not set
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_I2C_SUPPORT=y