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/Cyrus_P5020_defconfig b/configs/Cyrus_P5020_defconfig
index b82a756..7633d08 100644
--- a/configs/Cyrus_P5020_defconfig
+++ b/configs/Cyrus_P5020_defconfig
@@ -10,6 +10,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_CONSOLE_MUX=y
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_BOARD_EARLY_INIT_R=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_GREPENV=y
 # CONFIG_CMD_FLASH is not set