ata: mvebu: use dev_read_addr() to get base address

It is strange to use devfdt_get_addr_ptr(), then cast the pointer
back to ulong because you could use devfdt_get_addr() without casting.

Convert it to dev_read_addr(), which is capable to CONFIG_OF_LIVE.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/ata/ahci_mvebu.c b/drivers/ata/ahci_mvebu.c
index 8be1826..7d82d2e 100644
--- a/drivers/ata/ahci_mvebu.c
+++ b/drivers/ata/ahci_mvebu.c
@@ -39,7 +39,7 @@
 	 */
 	board_ahci_enable();
 
-	ahci_probe_scsi(dev, (ulong)devfdt_get_addr_ptr(dev));
+	ahci_probe_scsi(dev, dev_read_addr(dev));
 
 	return 0;
 }