of/flattree: Don't assume HAVE_LMB

We don't always have lmb available, so make arches provide an
early_init_dt_alloc_memory_arch() to handle the allocation of
memory in the fdt code.

When we don't have lmb.h included, we need asm/page.h for __va.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/prom.c

@@ -55,6 +55,11 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 	lmb_add(base, size);
 }
 
+u64 __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+	return lmb_alloc(size, align);
+}
+
 #ifdef CONFIG_EARLY_PRINTK
 /* MS this is Microblaze specifig function */
 static int __init early_init_dt_scan_serial(unsigned long node,