PCI: hv: Remove the bogus test in hv_eject_device_work()

When kernel is executing hv_eject_device_work(), hpdev->state value must
be hv_pcichild_ejecting; any other value would consist in a bug,
therefore replace the bogus check with an explicit WARN_ON() on the
condition failure detection.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jack Morgenstein <jackm@mellanox.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>