wpa_cli: Send ALL_STA command to the correct interface

wpa_cli: Send ALL_STA command to the correct interface

wpa_ctrl_command_sta(), called by the "ALL_STA" handler, didn't consider
ifname_prefix, resulting in various commands being sent to the global
control interface, rather than the specified interface when IFNAME=
prefix was used.

This in turn caused the unexpected "UNKNOWN COMMAND" result be
considered as valid station, resulting in infinite loop while trying to
get all stations.

Fix it by considering ifname_prefix, similarly to _wpa_ctrl_command().

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>