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/omap3_evm_defconfig b/configs/omap3_evm_defconfig
index 26d0e65..8b17192 100644
--- a/configs/omap3_evm_defconfig
+++ b/configs/omap3_evm_defconfig
@@ -9,6 +9,7 @@
 CONFIG_SPL=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_TPL_SYS_MALLOC_F_LEN=0x400
+CONFIG_USE_PREBOOT=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_DEFAULT_FDT_FILE="omap3-evm.dtb"
 CONFIG_VERSION_VARIABLE=y