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/C29XPCIE_SPIFLASH_SECBOOT_defconfig b/configs/C29XPCIE_SPIFLASH_SECBOOT_defconfig
index ffb0bf7..cda4dc4 100644
--- a/configs/C29XPCIE_SPIFLASH_SECBOOT_defconfig
+++ b/configs/C29XPCIE_SPIFLASH_SECBOOT_defconfig
@@ -11,6 +11,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="SPIFLASH"
 CONFIG_BOOTDELAY=-1
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
+CONFIG_BOARD_EARLY_INIT_R=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_EEPROM=y