Remove SAVE_CONFIG redirect from global control interface

Remove SAVE_CONFIG redirect from global control interface

The P2P redirection for SAVE_CONFIG issued on the global control
interface was preventing wpas_global_ctrl_iface_save_config() from being
reached. The global version of SAVE_CONFIG was supposed to try to save
configuration files for all interface rather than just the P2P
management interface, so fix this by removing the unneeded and undesired
redirection.

Modify the global SAVE_CONFIG handler to return FAIL if no configuration
files were saved. This makes the behavior match with the per-interface
SAVE_CONFIG.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>