mark user FPU context initialized, if current context is user context.
It was reversed in r215865, by inadequate change of this code fragment
to a call to fpuuserinited()/npxuserinited().
The issue is only relevant for in-kernel users of FPU.
Reported by: Jan Henrik Sylvester <me janh de>, Mike Tancsa <mike sentex net>
Tested by: Mike Tancsa
MFC after: 3 days