test/mem: fix page size for external memory

test/mem: fix page size for external memory

Currently external memory test uses 4K page size.
VFIO DMA mapping works only with system page granularity.

Earlier it was working because all the contiguous mappings
were coalesced and mapped in one-go which ended up becoming
a lot bigger page. Now that VFIO DMA mappings both in IOVA as VA
and IOVA as PA mode, are being done at memseg list granularity,
we need to use system page size.

Fixes: b270daa43b3d ("test: support external memory")
Cc: stable@dpdk.org
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>