Staging: wlan-ng: removed duplicate code in p80211req.c

This patch removes duplicate code in p80211req_mibset_mibget()
by adding p80211req_handle_action() function.

Changes since v1:
Removed prototype of p80211req_handle_action() from the prototype
list and add directly the function definition.

Signed-off-by: Claudiu Beznea <claudiu.beznea@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>