PCI/msi: fix the pci_alloc_irq_vectors_affinity stub

[ Upstream commit 83b4605b ]

We need to return an error for any call that asks for MSI / MSI-X
vectors only, so that non-trivial fallback logic can work properly.

Also valid dev->irq and use the "correct" errno value based on feedback
from Linus.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Fixes: aff17164 ("PCI: Provide sensible IRQ vector alloc/free routines")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/pci.h

@@ -1348,9 +1348,9 @@ static inline int pci_alloc_irq_vectors(struct pci_dev *dev,
 		unsigned int min_vecs, unsigned int max_vecs,
 		unsigned int flags)
 {
-	if (min_vecs > 1)
-		return -EINVAL;
-	return 1;
+	if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1 && dev->irq)
+		return 1;
+	return -ENOSPC;
 }
 static inline void pci_free_irq_vectors(struct pci_dev *dev)
 {