ARM: 7993/1: mm/memblock: add memblock_get_current_limit

ARM: 7993/1: mm/memblock: add memblock_get_current_limit

Apart from setting the limit of memblock, it's also useful to be able
to get the limit to avoid recalculating it every time. Add the function
to do so.

Acked-by: Catalin Marinas <[email protected]>
Acked-by: Santosh Shilimkar <[email protected]>
Acked-by: Andrew Morton <[email protected]>
Acked-by: Nicolas Pitre <[email protected]>
Signed-off-by: Laura Abbott <[email protected]>
Signed-off-by: Russell King <[email protected]>