The mvebu host controller driver allocates an msi_controller structure
pointer without allocating the structure and initializing its methods,
which makes the pointer useless.

This means that the PCI IRQ MSI layer ignores it and that after all it
should not really be needed.

Remove it.

Link: https://lore.kernel.org/r/20200904142132.6054-1-lorenzo.pieralisi@arm.comSigned-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>