net: Make sure IPaddr_t is 32 bits in size

When building u-boot as 64 bit application (e.g. sandbox) ulong might be
64 bits in size. This breaks network code as IPaddr_t is 64 bytes in
size then and an IPv4 address is 32 bits in size. This patch makes sure
that IPaddr_t is always 32 bits in size. Also some warnings introduced
by this patch are fixed.

Signed-off-by: Matthias Weisser <weisserm@arcor.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/net/nfs.c b/net/nfs.c
index 5e717e3..b5b482c 100644
--- a/net/nfs.c
+++ b/net/nfs.c
@@ -688,7 +688,7 @@
 	}
 
 	if (BootFile[0] == '\0') {
-		sprintf (default_filename, "/nfsroot/%02lX%02lX%02lX%02lX.img",
+		sprintf(default_filename, "/nfsroot/%02X%02X%02X%02X.img",
 			NetOurIP & 0xFF,
 			(NetOurIP >>  8) & 0xFF,
 			(NetOurIP >> 16) & 0xFF,