arm64: Introduce VA_BITS and translation level options

arm64: Introduce VA_BITS and translation level options

This patch adds virtual address space size and a level of translation
tables to kernel configuration. It facilicates introduction of
different MMU options, such as 4KB + 4 levels, 16KB + 4 levels and
64KB + 3 levels, easily.

The idea is based on the discussion with Catalin Marinas:
http://www.spinics.net/linux/lists/arm-kernel/msg319552.html

Signed-off-by: Jungseok Lee <[email protected]>
Reviewed-by: Sungjinn Chung <[email protected]>
Acked-by: Kukjin Kim <[email protected]>
Reviewed-by: Christoffer Dall <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>
Tested-by: Jungseok Lee <[email protected]>