x86: fix memalign() parameter order

Purely by code inspection, it looks like the parameter order to memalign()
is swapped; its parameters are (align, size). 4096 is a likely desired
alignment, and a variable named size sounds like a size:-)

Fixes: 45b5a37836 ("x86: Add multi-processor init")
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/mp_init.c

@@ -243,7 +243,7 @@ static int load_sipi_vector(atomic_t **ap_countp, int num_cpus)
 
 	params->stack_size = CONFIG_AP_STACK_SIZE;
 	size = params->stack_size * num_cpus;
-	stack = memalign(size, 4096);
+	stack = memalign(4096, size);
 	if (!stack)
 		return -ENOMEM;
 	params->stack_top = (u32)(stack + size);