mac80211: support wildcard paths when matching phys

This change introduces support for wildcard patterns in "option path"
of section "wifi-device".

Objective is to allow paths like "*/usb[0-9]/*/*" in order to claim
any usb device using the same backend type, regardless of its bus
address or phy name.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

SVN-Revision: 41873