mm/memblock.c: expose total reserved memory

mm/memblock.c: expose total reserved memory

The total reserved memory in a system is accounted but not available for
use use outside mm/memblock.c.  By exposing the total reserved memory,
systems can better calculate the size of large hashes.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Srikar Dronamraju <[email protected]>
Suggested-by: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mahesh Salgaonkar <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>