mempool: fix virtual address population

mempool: fix virtual address population

Currently, populate_virt will check if mempool is already populated.
This will cause inability to reserve multi-chunk mempools if
contiguous memory is not a hard requirement, because if allocating
all-contiguous memory fails, mempool will retry with virtual addresses
and will call populate_virt. It seems that the original code never
anticipated more than one non-physically contiguous area.

Fix it by removing the check in populate virt. populate_anon() function
calls populate_virt() also, and it can be reasonably inferred that it is
expecting that virtual area is not already populated. Even though a
similar check is already in place there, also add the check that was
part of populate_virt() just in case.

Fixes: aab4f62d6c1c ("mempool: support no hugepage mode")
Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>