Building the tegra PCIe host driver without MSI results in a link
failure:

drivers/pci/host/pci-tegra.o:(.data+0x70): undefined reference to
`pci_msi_unmask_irq'
drivers/pci/host/pci-tegra.o:(.data+0x74): undefined reference to
`pci_msi_mask_irq'

This adds the same dependency that everyone else uses.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[lorenzo.pieralisi@arm.com: rewrote commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thierry Reding <treding@nvidia.com>