ARM: 7113/1: mm: Align bank start to MAX_ORDER_NR_PAGES

The VM subsystem assumes that there are valid memmap entries from
the bank start aligned to MAX_ORDER_NR_PAGES.

On the Ux500 we have a lot of mem=N arguments on the commandline
triggering this bug several times over and causing kernel
oops messages.

Cc: stable@kernel.org
Cc: Michael Bohan <mbohan@codeaurora.org>
Cc: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Johan Palsson <johan.palsson@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>