MSI: Add an arch_msi_check_device()

Add an arch_check_device(), which gives archs a chance to check the input
to pci_enable_msi/x. The arch might be interested in the value of nvec so
pass it in. Propagate the error value returned from the arch routine out
to the caller.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/msi.h b/include/linux/msi.h
index e38fe682..d2a2000 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -41,6 +41,7 @@
  */
 int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc);
 void arch_teardown_msi_irq(unsigned int irq);
+extern int arch_msi_check_device(struct pci_dev* dev, int nvec, int type);
 
 
 #endif /* LINUX_MSI_H */