pmu: fix conditions for emulation test

Right now, unittests.cfg only supports a single check line.  Multiple
checks must be space separated.

However, the pmu_emulation test does not really need nmi_watchdog=0;
it is only needed by the PMU counters test because Linux reserves one
counter if nmi_watchdog=1, but the pmu_emulation test does not
allocate all counters in the same way.  By removing the counters
tests from pmu_emulation, the check on nmi_watchdog=0 can be
removed.

This also hid a typo for the force_emulation_prefix module parameter,
which is part of the kvm module rather than the kvm_intel module,
so fix that.

Reported-by: Like Xu <like.xu.linux@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>