ARM: 8636/1: Cleanup sanity_check_meminfo

The logic for sanity_check_meminfo has become difficult to
follow. Clean up the code so it's more obvious what the code
is actually trying to do. Additionally, meminfo is now removed
so rename the function to better describe its purpose.

Tested-by: Magnus Lilja <lilja.magnus@gmail.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>