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/brppt1_spi_defconfig b/configs/brppt1_spi_defconfig
index ce7c852..9d629f6 100644
--- a/configs/brppt1_spi_defconfig
+++ b/configs/brppt1_spi_defconfig
@@ -11,6 +11,7 @@
 CONFIG_ENV_OFFSET=0x20000
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_SPL=y
+CONFIG_ENV_SECT_SIZE=0x10000
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_TPL_SYS_MALLOC_F_LEN=0x0
@@ -21,6 +22,8 @@
 CONFIG_BOOTDELAY=0
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="run b_default"
+CONFIG_USE_PREBOOT=y
+CONFIG_PREBOOT="run cfgscr; run brdefaultip"
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
@@ -70,7 +73,6 @@
 CONFIG_DEFAULT_DEVICE_TREE="am335x-brppt1-spi"
 CONFIG_OF_SPL_REMOVE_PROPS="pinctrl-0 pinctrl-names clocks clock-names interrupt-parent interrupt-controller interrupt-cells dma-names dmas "
 CONFIG_ENV_IS_IN_SPI_FLASH=y
-CONFIG_ENV_SECT_SIZE=0x10000
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM=y
 CONFIG_SPL_DM=y