x86/PCI: Include function number in $PIR table dump

Contrary to the PCI BIOS specification[1] some systems include the PCI 
function number for motherboard devices in their $PIR table, e.g. this 
is what the Tyan Tomcat IV S1564D board reports:

00:14 slot=01
 0:60/deb8
 1:61/deb8
 2:62/deb8
 3:63/deb8

00:13 slot=02
 0:61/deb8
 1:62/deb8
 2:63/deb8
 3:60/deb8

00:12 slot=03
 0:62/deb8
 1:63/deb8
 2:60/deb8
 3:61/deb8

00:11 slot=04
 0:63/deb8
 1:60/deb8
 2:61/deb8
 3:62/deb8

00:07 slot=00
 0:00/deb8
 1:00/deb8
 2:00/deb8
 3:00/deb8

00:07 slot=00
 0:00/deb8
 1:00/deb8
 2:00/deb8
 3:63/deb8

Print the function number then in the debug $PIR table dump:

00:14.0 slot=01
 0:60/deb8
 1:61/deb8
 2:62/deb8
 3:63/deb8

00:13.0 slot=02
 0:61/deb8
 1:62/deb8
 2:63/deb8
 3:60/deb8

00:12.0 slot=03
 0:62/deb8
 1:63/deb8
 2:60/deb8
 3:61/deb8

00:11.0 slot=04
 0:63/deb8
 1:60/deb8
 2:61/deb8
 3:62/deb8

00:07.1 slot=00
 0:00/deb8
 1:00/deb8
 2:00/deb8
 3:00/deb8

00:07.2 slot=00
 0:00/deb8
 1:00/deb8
 2:00/deb8
 3:63/deb8

References:

[1] "PCI BIOS Specification", Revision 2.1, PCI Special Interest Group, 
    August 26, 1994, Table 4-1 "Layout of IRQ routing table entry.", p. 
    12
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203301534440.22465@angie.orcam.me.uk

arch/x86/pci/irq.c

@@ -135,7 +135,8 @@ static void __init pirq_peer_trick(void)
 #ifdef DEBUG
 		{
 			int j;
-			DBG(KERN_DEBUG "%02x:%02x slot=%02x", e->bus, e->devfn/8, e->slot);
+			DBG(KERN_DEBUG "%02x:%02x.%x slot=%02x",
+			    e->bus, e->devfn / 8, e->devfn % 8, e->slot);
 			for (j = 0; j < 4; j++)
 				DBG(" %d:%02x/%04x", j, e->irq[j].link, e->irq[j].bitmap);
 			DBG("\n");