Add "name" field to struct device to allow human-readable hardware device

names.

Add "dev" pointer in struct net_device to tie network interfaces back to a
hardware device.

Force natural alignment of data types in __table() macros.  This seems to
prevent gcc from taking the unilateral decision to occasionally increase
their alignment (which screws up the table packing).

src/include/gpxe/errortab.h

@@ -15,6 +15,6 @@ struct errortab {
 	const char *text;
 };
 
-#define __errortab __table ( errortab, 01 )
+#define __errortab __table ( struct errortab, errortab, 01 )
 
 #endif /* _GPXE_ERRORTAB_H */