mem: raise maximum fd limit unconditionally

mem: raise maximum fd limit unconditionally

Previously, when we allocated hugepages, we closed the fd's corresponding
to them after we've done our mappings. Since we did mmap(), we didn't
actually lose the reference, but file descriptors used for mmap() do not
count against the fd limit. Since we are going to store all of our fd's,
we will hit the fd limit much more often when using smaller page sizes.

Fix this to raise the fd limit to maximum unconditionally.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>