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/MPC8548CDS_defconfig b/configs/MPC8548CDS_defconfig
index 0ddc63a..b579315 100644
--- a/configs/MPC8548CDS_defconfig
+++ b/configs/MPC8548CDS_defconfig
@@ -6,6 +6,7 @@
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_BOOTDELAY=10
+# CONFIG_MISC_INIT_R is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_I2C=y