eal: move runtime directory creation after args parsing

eal: move runtime directory creation after args parsing

The intention of the original code was to create runtime data
directory as early as possible, however it was moved too early,
before the arguments were parsed, resulting in --file-prefix
option essentially not working.

Fix this by moving eal_create_runtime_dir() to after command
line arguments parsing.

Fixes: 56236363b481 ("eal: add directory for runtime data")

Reported-by: Andrew Rybchenko <arybchenko@solarflare.com>
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Tested-by: Andrew Rybchenko <arybchenko@solarflare.com>