core: fdtaddr: use map_sysmem() as cast for the return

For the devfdt_get_addr_index_ptr() and devfdt_get_addr_size_index_ptr()
function use map_sysmem() function as cast for the return for use in
sandbox. Also fix sandbox test.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Drop second hunk:
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/test-fdt.c b/test/dm/test-fdt.c
index 8e6e42e..eeecd1d 100644
--- a/test/dm/test-fdt.c
+++ b/test/dm/test-fdt.c
@@ -617,6 +617,7 @@
 {
 	struct udevice *gpio, *dev;
 	void *ptr;
+	void *paddr;
 
 	/* Test for missing reg property */
 	ut_assertok(uclass_first_device_err(UCLASS_GPIO, &gpio));
@@ -624,7 +625,9 @@
 
 	ut_assertok(uclass_find_device_by_seq(UCLASS_TEST_DUMMY, 0, &dev));
 	ptr = devfdt_get_addr_ptr(dev);
-	ut_asserteq_ptr((void *)0x8000, ptr);
+
+	paddr = map_sysmem(0x8000, 0);
+	ut_asserteq_ptr(paddr, ptr);
 
 	return 0;
 }