Fix all calls to functions in eal_filesystem to produce paths
residing inside dedicated DPDK runtime directory. Leaving DPDK
runtime config in place as 3rd-party applications within the
DPDK ecosystem might rely on this path to determine whether
DPDK is running, so moving that will be postponed to the next
release cycle.
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>