mempool: detect physical contiguous objects

mempool: detect physical contiguous objects

The memory area containing all the objects must be physically
contiguous.
Introducing MEMPOOL_F_CAPA_PHYS_CONTIG flag for such use-case.

The flag useful to detect whether pool area has sufficient space
to fit all objects. If not then return -ENOSPC.
This way, we make sure that all object within a pool is contiguous.

Signed-off-by: Santosh Shukla <santosh.shukla@caviumnetworks.com>
Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>