ARM: move memory layout sanity checking before meminfo initialization

Ensure that the meminfo array is sanity checked before we pass the
memory to memblock.  This helps to ensure that memblock and meminfo
agree on the dimensions of memory, especially when more memory is
passed than the kernel can deal with.

Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>