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/T1023RDB_defconfig b/configs/T1023RDB_defconfig
index ad4a77b..41e88b7 100644
--- a/configs/T1023RDB_defconfig
+++ b/configs/T1023RDB_defconfig
@@ -8,6 +8,7 @@
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_BOOTDELAY=10
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
+CONFIG_BOARD_EARLY_INIT_R=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_GREPENV=y