xen/arm: fix duplicate memory node in DT

When reserved-memory regions are present in the host device tree, dom0
is started with multiple memory nodes. Each memory node should have a
unique name, but today they are all called "memory" leading to Linux
printing the following warning at boot:

  OF: Duplicate name in base, renamed to "memory#1"

This patch fixes the problem by appending a "@<unit-address>" to the
name, as per the Device Tree specification, where <unit-address> matches
the base of address of the first region.

Fixes: 248faa637d (xen/arm: add reserved-memory regions to the dom0 memory node)
Reported-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Release-acked-by: Juergen Gross <jgross@suse.com>

xen/arch/arm/domain_build.c

@@ -646,6 +646,8 @@ static int __init make_memory_node(const struct domain *d,
     int res, i;
     int reg_size = addrcells + sizecells;
     int nr_cells = reg_size * mem->nr_banks;
+    /* Placeholder for memory@ + a 64-bit number + \0 */
+    char buf[24];
     __be32 reg[NR_MEM_BANKS * 4 /* Worst case addrcells + sizecells */];
     __be32 *cells;
 
@@ -657,7 +659,8 @@ static int __init make_memory_node(const struct domain *d,
                reg_size, nr_cells);
 
     /* ePAPR 3.4 */
-    res = fdt_begin_node(fdt, "memory");
+    snprintf(buf, sizeof(buf), "memory@%"PRIx64, mem->bank[0].start);
+    res = fdt_begin_node(fdt, buf);
     if ( res )
         return res;