Tuned RTC wakeup wakelock handling

Minimum stay-alive period shortened to 2 seconds if no clients
make keep alive request, or to 4 seconds if at least one client
comes through.

The rtc wakeup wakelock name is now in sync with the dsme side.

If mce is build without wakelock support (i.e. no autosuspend
policy), the cpu keepalive period is 1 day instead of 1 minute
to reduce the amount of unnecessary ipc.

Also fixes error handling for dbus name owner queries.
Allow user processes to make cpu-keepalive method calls