config_cmd_defaults.h: new header for common u-boot command defaults

We have config_defaults.h which are random configuration settings that
everyone gets by default.  We also have config_cmd_default.h which is a
recommended list of defaults but boards have to opt into.  Now we have
config_cmd_defaults.h which is a list of defaults that everyone gets
and has to actively opt out of.

For now, we populate it with the bootm command which previously was
unable to be disabled.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/mkconfig b/mkconfig
index 2fda1d4..db69336 100755
--- a/mkconfig
+++ b/mkconfig
@@ -155,6 +155,7 @@
 
 cat << EOF >> config.h
 #define CONFIG_BOARDDIR board/$BOARDDIR
+#include <config_cmd_defaults.h>
 #include <config_defaults.h>
 #include <configs/${CONFIG_NAME}.h>
 #include <asm/config.h>