ARM: move initialization of the high_memory variable earlier

Some upcoming changes must know the VMALLOC_START value, which is based
on high_memory, before bootmem_init() is called.

The best location to set it is in sanity_check_meminfo() where the needed
computation is already done, and in the non MMU case it is trivial to do
now that the meminfo array is already sorted at that point.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index dc8c550..0aa8b7d 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -860,6 +860,7 @@
 	}
 #endif
 	meminfo.nr_banks = j;
+	high_memory = __va(lowmem_limit - 1) + 1;
 	memblock_set_current_limit(lowmem_limit);
 }