[Fix] limited the input taken by sscanf for ip and mac address

[Fix] limited the input taken by sscanf for ip and mac address

Description: This patch also fixes some warinings as below:
1. assigned value of rv was over written in __ws_p2p_supplicant_start
	and __ws_p2p_supplicant_stop funtions.
2. In _ws_reset_plugin the name of in variable was conflicting with
	global variable g_pd, so replced g_pd in this funtion with f_pd
	to differ between global and funtion param.

Change-Id: I29c231bf859736995b9c604bb7088be976406401
Signed-off-by: Nishant Chaprana <n.chaprana@samsung.com>