vdpa/mlx5: Fix wrong use of bit numbers

VIRTIO_F_VERSION_1 is a bit number. Use BIT_ULL() with mask
conditionals.

Also, in mlx5_vdpa_is_little_endian() use BIT_ULL for consistency with
the rest of the code.

Fixes: 1a86b377

 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210408091047.4269-5-elic@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>