net: fix ULI 526x macro usage in netdev.h

Change netdev.h to use CONFIG_ULI526X instead of CONFIG_ULI526.  CONFIG_ULI526X
is used everywhere else, so that's the correct macro name.  Without this fix,
Ethernet will not work on the Freescale MPC8610 HPCD.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>

include/netdev.h

@@ -108,7 +108,7 @@ static inline int pci_eth_init(bd_t *bis)
 #if defined(CONFIG_RTL8169)
 	num += rtl8169_initialize(bis);
 #endif
-#if defined(CONFIG_ULI526)
+#if defined(CONFIG_ULI526X)
 	num += uli526x_initialize(bis);
 #endif