PCI: designware: Reject MSI-X IRQs

PCI: designware: Reject MSI-X IRQs

The DesignWare PCIe MSI hardware does not support MSI-X IRQs.  Setting
those up failed as a side effect of a bug which was fixed by 91f8ae823f2b
("PCI: designware: Setup and clear exactly one MSI at a time").

Now that this bug is fixed, MSI-X IRQs need to be rejected explicitly;
otherwise devices trying to use them may end up with incorrectly working
interrupts.

Fixes: 91f8ae823f2b ("PCI: designware: Setup and clear exactly one MSI at a time")
Signed-off-by: Lucas Stach <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Acked-by: Jingoo Han <[email protected]>
CC: [email protected]	# v3.18+