x86, MSI: pass irq_cfg and irq_desc

Impact: simplify code

Pass irq_desc and cfg around, instead of raw IRQ numbers - this way
we dont have to look it up again and again.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 8f29392..d2b8a1e 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -10,8 +10,11 @@
 };
 
 /* Helper functions */
+struct irq_desc;
 extern void mask_msi_irq(unsigned int irq);
 extern void unmask_msi_irq(unsigned int irq);
+extern void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
+extern void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg);
 extern void read_msi_msg(unsigned int irq, struct msi_msg *msg);
 extern void write_msi_msg(unsigned int irq, struct msi_msg *msg);