cpu: fix memleak of 'halt_cond' and 'thread'

cpu: fix memleak of 'halt_cond' and 'thread'

Since a4c2735f35 (cpu: move Qemu[Thread|Cond] setup into common code,
2024-05-30) these fields are now allocated at cpu_common_initfn(). So
let's make sure we also free them at cpu_common_finalize().

Furthermore, the code also frees these on round robin, but we missed
'halt_cond'.

Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>