mem: get physical address of any rte_malloc buffer

mem: get physical address of any rte_malloc buffer

Get physical address of any rte_malloc allocated buffer using
function rte_malloc_virt2phy(addr).
The rte_memzone pointer is now stored in each allocated memory block
header to allow simple computation of physical address of a block
using the memzone it comes from.
The function rte_malloc_virt2phy has a dependency on rte_memory.h:
phys_addr_t must be defined.

Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>