Convert CONFIG_MISC_INIT_R to Kconfig

This converts the following to Kconfig:
   CONFIG_MISC_INIT_R

Signed-off-by: Adam Ford <aford173@gmail.com>
[trini: Update the defaults logic slightly]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/stm32f469-discovery_defconfig b/configs/stm32f469-discovery_defconfig
index ccfe09b..8a62ec7 100644
--- a/configs/stm32f469-discovery_defconfig
+++ b/configs/stm32f469-discovery_defconfig
@@ -9,6 +9,7 @@
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_BOOTDELAY=3
 # CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_MISC_INIT_R=y
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SYS_PROMPT="U-Boot > "