MFC r259197:

MFC r259197:
Do not DELAY() for P-state transition unless we want to see the result.

Intel manual says: "If a transition is already in progress, transition to
a new value will subsequently take effect. Reads of IA32_PERF_CTL determine
the last targeted operating point."  So seems it should be fine to just
trigger wanted transition and go.  Linux does the same.

git-svn-id: svn://svn.freebsd.org/base/stable/8@260602 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f