Convert CONFIG_REMAKE_ELF to Kconfig

This converts the following to Kconfig:
   CONFIG_REMAKE_ELF

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
diff --git a/configs/libretech-ac_defconfig b/configs/libretech-ac_defconfig
index 945521b..be6fbe8 100644
--- a/configs/libretech-ac_defconfig
+++ b/configs/libretech-ac_defconfig
@@ -13,6 +13,7 @@
 CONFIG_DEBUG_UART_CLOCK=24000000
 CONFIG_IDENT_STRING=" libretech-ac"
 CONFIG_DEBUG_UART=y
+CONFIG_REMAKE_ELF=y
 CONFIG_SYS_LOAD_ADDR=0x1000000
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_USE_PREBOOT=y