[ARM] arm32: Align to 4KB instead of 1MB at boot-time

We are no longer creating 1MB section entries at boot-time hence
no need to align Xvisor to 1MB. Instead we need to align it to
4KB boundary because we now create 4KB page entries at boot-time.

Signed-off-by: Anup Patel <anup@brainfault.org>