PCI: hv: Drop msi_controller structure

PCI: hv: Drop msi_controller structure

The Hyper-V PCI driver still makes use of a msi_controller structure,
but it looks more like a distant leftover than anything actually
useful, since it is initialised to 0 and never used for anything.

Just remove it.

Link: https://lore.kernel.org/r/20210330151145.997953-7-maz@kernel.org
Tested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>