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/socfpga_agilex_defconfig b/configs/socfpga_agilex_defconfig
index 3559633..2e116fb 100644
--- a/configs/socfpga_agilex_defconfig
+++ b/configs/socfpga_agilex_defconfig
@@ -15,6 +15,7 @@
 CONFIG_IDENT_STRING="socfpga_agilex"
 CONFIG_SPL_FS_FAT=y
 # CONFIG_PSCI_RESET is not set
+CONFIG_REMAKE_ELF=y
 CONFIG_SYS_LOAD_ADDR=0x02000000
 CONFIG_BOOTDELAY=5
 CONFIG_USE_BOOTARGS=y