interrupt resource clean up

[Mike Tancsa]

While trying to debug an issue with an em nic, I noticed that if I
unload the kld which previously had the nic using multiple msi
interrupts, and then load it with msix disabled, vmstat -i shows some
funny output

e.g. before

interrupt                          total       rate
irq4: uart0                        37945          0
irq16: siis0                    90443357         55
irq18: arcmsr0                 138839249         84
irq19: bge0 twa0                 4642943          2
irq21: ehci0                    11565862          7
irq23: ehci1                     3279942          2
cpu0: timer                   3279559638       2000
irq256: em0                   1609329648        981
irq257: em1:rx 0               756066703        461
irq258: em1:tx 0               595711018        363
irq259: em1:link                   41186          0
irq260: ahci0                   94752814         57
cpu1: timer                   3279552436       2000
cpu3: timer                   3279552195       2000
cpu2: timer                   3279550937       2000
Total                        16422925873      10015


and after

# vmstat -i
interrupt                          total       rate
irq4: uart0                        42144          0
irq16: siis0                    93796258         54
irq18: arcmsr0                 144244159         83
irq19: bge0 twa0                 4840729          2
irq21: ehci0                    12015466          6
irq23: ehci1                     3436876          2
cpu0: timer                   3436486096       2000
irq256: em0                   1719107713       1000
irq257: em1                    767271792        446
irq258:                        605077993        352
irq259:                            41186          0
irq260: ahci0                   98454608         57
cpu1: timer                   3436478875       2000
cpu3: timer                   3436478653       2000
cpu2: timer                   3436477132       2000
Total                        17194249680      10007

Is this just a display issue, or are the resources still allocated ?

	---Mike