PCI MSI: Add support for multiple MSI

Add the new API pci_enable_msi_block() to allow drivers to
request multiple MSI and reimplement pci_enable_msi in terms of
pci_enable_msi_block.  Ensure that the architecture back ends don't
have to know about multiple MSI.

Signed-off-by: Matthew Wilcox <[email protected]>
Signed-off-by: Jesse Barnes <[email protected]>
7 files changed