Fix a couple of issues with the ibcs2 module event handler.  First, return success instead of EOPNOTSUPP when being loaded.  Secondly, if there are no ibcs2 processes running when a MOD_UNLOAD request is made, break out to return success instead of falling through into the default case which returns EOPNOTSUPP.  With these fixes, I can now kldload and subsequently kldunload the ibcs2 module.
Fix a couple of issues with the ibcs2 module event handler.  First, return
success instead of EOPNOTSUPP when being loaded.  Secondly, if there are no
ibcs2 processes running when a MOD_UNLOAD request is made, break out to
return success instead of falling through into the default case which
returns EOPNOTSUPP.  With these fixes, I can now kldload and subsequently
kldunload the ibcs2 module.

PR:		kern/82026 (and several duplicates)
Reported by:	lots of folks
MFC after:	1 week

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