upl: fix parsing of DT property

When calling decode_addr_size() we must pass the size of the device-tree
property and not sizeof(void *).

Fixes: 90469da3da0d ("upl: Add support for reading a upl handoff")
Addresses-Coverity-ID: 510459 Wrong sizeof argument
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/boot/upl_read.c b/boot/upl_read.c
index 5063897..be3e1d1 100644
--- a/boot/upl_read.c
+++ b/boot/upl_read.c
@@ -520,7 +520,7 @@
 		return log_msg_ret("reg", -EINVAL);
 	}
 
-	len = decode_addr_size(upl, buf, sizeof(buf), &gra->reg);
+	len = decode_addr_size(upl, buf, size, &gra->reg);
 	if (len < 0)
 		return log_msg_ret("buf", len);