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/nitrogen6s_defconfig b/configs/nitrogen6s_defconfig
index 458b9da..985eb3d 100644
--- a/configs/nitrogen6s_defconfig
+++ b/configs/nitrogen6s_defconfig
@@ -8,6 +8,7 @@
 CONFIG_BOOTDELAY=3
 CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE=y
 CONFIG_SUPPORT_RAW_INITRD=y
+CONFIG_MISC_INIT_R=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y