target-arm/arm-powerctl: wake up sleeping CPUs

target-arm/arm-powerctl: wake up sleeping CPUs

Testing with Alexander's bare metal syncronisation tests fails in MTTCG
leaving one CPU spinning forever waiting for the second CPU to wake up.
We simply need to kick the vCPU once we have processed the PSCI power on
call.

As the power control API is for system emulation only as is the
qemu_kick_cpu function we also ensure we only build arm-powerctl for
SoftMMU builds.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
CC: Alexander Spyridakis <a.spyridakis@virtualopensystems.com>
Message-Id: <1439220437-23957-20-git-send-email-fred.konrad@greensocs.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20161027151030.20863-11-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>