igb_uio: switch to new irq function for MSI-X

igb_uio: switch to new irq function for MSI-X

pci_enable_msix() will be removed in kernel 4.12.
The new API pci_alloc_irq_vectors() is available
since linux 4.8, thus let's use it.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=aff171641d18
Link: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=4244de1c64de
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: David Marchand <david.marchand@6wind.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>