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/am335x_shc_defconfig b/configs/am335x_shc_defconfig
index 212c884..5953193 100644
--- a/configs/am335x_shc_defconfig
+++ b/configs/am335x_shc_defconfig
@@ -23,6 +23,9 @@
 CONFIG_AUTOBOOT_PROMPT="Enter 'shc' to enter prompt (times out) %d \nEnter 'noautoboot' to enter prompt without timeout\n"
 CONFIG_AUTOBOOT_DELAY_STR="shc"
 CONFIG_AUTOBOOT_STOP_STR="noautoboot"
+CONFIG_BOOT_RETRY=y
+CONFIG_BOOT_RETRY_TIME=30
+CONFIG_RESET_TO_RETRY=y
 CONFIG_BOOTCOMMAND="if mmc dev 1; mmc rescan; then run emmc_setup; else echo ERROR: eMMC device not detected!; panic; fi; if run loaduimage; then run mmcboot; else echo ERROR Unable to load uImage from eMMC!; echo Performing Rollback!; setenv _active_ ${active_root}; setenv _inactive_ ${inactive_root}; setenv active_root ${_inactive_}; setenv inactive_root ${_active_}; saveenv; reset; fi; "
 CONFIG_DEFAULT_FDT_FILE="am335x-shc"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y