If "[*]" is given as the last part of a QOM property name, treat that
as an array property. The added property is given the first available
name, replacing the * with a decimal number counting from 0.

First add with name "foo[*]" will be "foo[0]". Second "foo[1]" and so
on.

Callers may inspect the ObjectProperty * return value to see what
number the added property was given.
Signed-off-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>