vfio: fix workaround of BAR mapping

vfio: fix workaround of BAR mapping

Currently, VFIO will try to map around MSI-X table in the BARs. When
MSI-X table (page-aligned) size is equal to (page-aligned) size of BAR,
VFIO will just skip the BAR.

Recent kernel versions will allow VFIO to map the entire BAR containing
MSI-X tables (*), so instead of trying to map around the MSI-X vector
or skipping the BAR entirely if it's not possible, we can now try
mapping the entire BAR first. If mapping the entire BAR doesn't
succeed, fall back to the old behavior of mapping around MSI-X table or
skipping the BAR.

(*): "vfio-pci: Allow mapping MSIX BAR",
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
commit/?id=a32295c612c57990d17fb0f41e7134394b2f35f6

Fixes: 90a1633b2347 ("eal/linux: allow to map BARs with MSI-X tables")

Signed-off-by: Takeshi Yoshimura <t.yoshimura8869@gmail.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>