of/fdt: remove redundant memset in __unflatten_device_tree()

Now that memblock and slab allocators are the only allocators and both
return zero-initialized memory, zeroing the memory ourselves is
redundant. The allocators used are:

- kernel_tree_alloc uses kzalloc()
- early_init_dt_alloc_memory_arch() and dt_alloc_memory() both use
  memblock_alloc()

Remove redundant memset after the allocation. No funtional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Link: https://patch.msgid.link/20260418140420.2221736-1-ekffu200098@gmail.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

drivers/of/fdt.c

@@ -391,8 +391,6 @@ void *__unflatten_device_tree(const void *blob,
 	if (!mem)
 		return NULL;
 
-	memset(mem, 0, size);
-
 	*(__be32 *)(mem + size) = cpu_to_be32(0xdeadbeef);
 
 	pr_debug("  unflattening %p...\n", mem);