net: warn about spaces in device names

Some commands operate on eth device names (like 'mii'), but those cannot
be passed on the command line as one argument.  So detect devices like
these and warn about them so someone will fix it.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NBen Warren <biggerbadderben@gmail.com>

net/eth.c

@@ -234,6 +234,9 @@ int eth_initialize(bd_t *bis)
 				puts (" [PRIME]");
 			}
 
+			if (strchr(dev->name, ' '))
+				puts("\nWarning: eth device name has a space!\n");
+
 			eth_getenv_enetaddr_by_index(eth_number, env_enetaddr);
 
 			if (memcmp(env_enetaddr, "\0\0\0\0\0\0", 6)) {