Convert CONFIG_USE_PREBOOT and CONFIG_PREBOOT to Kconfig

This converts the following to Kconfig:
   CONFIG_USE_PREBOOT
   CONFIG_PREBOOT

Both are together in one commit, since otherwise the former causes kconfig
to define the latter, which gives duplicate symbol errors.

Includes a manual fixup for CONFIG_PREBOOT in ids8313_defconfig since the
backslash lands in the wrong place. Similarly with socfpga_vining_fpga.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/bcm7445_defconfig b/configs/bcm7445_defconfig
index f22b06e..c79de19 100644
--- a/configs/bcm7445_defconfig
+++ b/configs/bcm7445_defconfig
@@ -6,6 +6,8 @@
 CONFIG_FIT=y
 CONFIG_FIT_SIGNATURE=y
 CONFIG_BOOTDELAY=1
+CONFIG_USE_PREBOOT=y
+CONFIG_PREBOOT="fdt addr ${fdtcontroladdr};fdt move ${fdtcontroladdr} ${fdtsaveaddr};fdt addr ${fdtsaveaddr};"
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot>"
 CONFIG_CMD_SF=y