drivers: eth_e1000: Fix build warning for x86_64

This patch allows to build Ethernet driver eth_e1000 for x86_64
boards.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
diff --git a/drivers/ethernet/eth_e1000.c b/drivers/ethernet/eth_e1000.c
index ec1053c..56292ff 100644
--- a/drivers/ethernet/eth_e1000.c
+++ b/drivers/ethernet/eth_e1000.c
@@ -251,7 +251,7 @@
 
 	/* Setup TX descriptor */
 
-	iow32(dev, TDBAL, (uint32_t) &dev->tx);
+	iow32(dev, TDBAL, (uint32_t)POINTER_TO_UINT(&dev->tx));
 	iow32(dev, TDBAH, 0);
 	iow32(dev, TDLEN, 1*16);
 
@@ -265,7 +265,7 @@
 	dev->rx.addr = POINTER_TO_INT(dev->rxb);
 	dev->rx.len = sizeof(dev->rxb);
 
-	iow32(dev, RDBAL, (uint32_t) &dev->rx);
+	iow32(dev, RDBAL, (uint32_t)POINTER_TO_UINT(&dev->rx));
 	iow32(dev, RDBAH, 0);
 	iow32(dev, RDLEN, 1*16);