As there is no driver using msi_controller, we can now safely
remove its use from the PCI probe code.

Link: https://lore.kernel.org/r/20210330151145.997953-8-maz@kernel.orgSigned-off-by: NMarc Zyngier <maz@kernel.org>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>