Convert CONFIG_BOOT_RETRY_TIME et al to Kconfig

This converts the following to Kconfig:
   CONFIG_BOOT_RETRY_TIME
   CONFIG_BOOT_RETRY_MIN
   CONFIG_RESET_TO_RETRY

We also introduce CONFIG_BOOT_RETRY to gate these options, and clean up
the associated Makefile entry and C code for picking default values of
CONFIG_BOOT_RETRY_MIN.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ids8313_defconfig b/configs/ids8313_defconfig
index 64e2a4c..ee7faf9 100644
--- a/configs/ids8313_defconfig
+++ b/configs/ids8313_defconfig
@@ -127,6 +127,10 @@
 CONFIG_AUTOBOOT_KEYED=y
 CONFIG_AUTOBOOT_PROMPT="Enter password - autoboot in %d seconds...\n"
 CONFIG_AUTOBOOT_DELAY_STR="ids"
+CONFIG_BOOT_RETRY=y
+CONFIG_BOOT_RETRY_TIME=900
+CONFIG_BOOT_RETRY_MIN=30
+CONFIG_RESET_TO_RETRY=y
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="run boot_cramfs"
 CONFIG_USE_PREBOOT=y