env: Include bootdelay in environment if negative

The test for (CONFIG_BOOTDELAY >= 0) has been in U-Boot since the
beginning, but the meaning of it has changed over time. Allow the
default to be set for any value, including -ve ones. This allows
(for example) CONFIG_ENV_IS_NOWHERE to have values for bootdelay in
its compiled in environment.

The only thing this changes is where the default for bootdelay can be
fetched from; before this change you get a compiled in default, after
you'll pull it from the default value in the environment, but both values
will be the same. Also if there's a value set in the environment then
that will take precedence (as before).

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>

include/env_default.h

@@ -40,7 +40,7 @@ const uchar default_environment[] = {
 #ifdef	CONFIG_NFSBOOTCOMMAND
 	"nfsboot="	CONFIG_NFSBOOTCOMMAND		"\0"
 #endif
-#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)
+#if defined(CONFIG_BOOTDELAY)
 	"bootdelay="	__stringify(CONFIG_BOOTDELAY)	"\0"
 #endif
 #if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0)