Kconfig: Migrate CONFIG_BOOTM_* options

Migrate all of the existing OS support options that are under
CONFIG_BOOTM_* to Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri-imx6ull_defconfig b/configs/colibri-imx6ull_defconfig
index 8c21ff4..99b3deb 100644
--- a/configs/colibri-imx6ull_defconfig
+++ b/configs/colibri-imx6ull_defconfig
@@ -16,6 +16,8 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_BOUNCE_BUFFER=y
 CONFIG_SYS_PROMPT="Colibri iMX6ULL # "
+# CONFIG_BOOTM_PLAN9 is not set
+# CONFIG_BOOTM_RTEMS is not set
 # CONFIG_CMD_ELF is not set
 # CONFIG_CMD_IMI is not set
 # CONFIG_CMD_XIMG is not set