vxge: fix memory leak in vxge_alloc_msix() error path

When pci_enable_msix() returned ret<0, entries and vxge_entries were leaked.
While at it, use the centralized exit idiom in the function.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Acked-by: Ram Vepa <ram.vepa@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>