Partprobe rereads disk structures to the kernel. After returning to caller the...

Partprobe rereads disk structures to the kernel. After returning to caller the process is sometimes not completed.
So information about labels, part labels are sometimes are not available. A small sleep solves this issue so far, but
a better synchronization method would be more appopriate but too complex for such a small tool. And atm a reliable
algorithm is not clear.

Signed-off-by: Thomas Mittelstaedt <thomas.mittelstaedt@de.bosch.com>