ANDROID: net: enable wireless core features with GKI_LEGACY_WEXT_ALLCONFIG

In embedded environments the requirements are to be able to pick and
chose which features one requires built into the kernel.  If an
embedded environment wants to supports loading modules that have been
kbuilt out of tree, there is a need to enable hidden configurations
for legacy wireless core features to provide the API surface for
them to load.

Introduce CONFIG_GKI_LEGACY_WEXT_ALLCONFIG to select all legacy wireless
extension core features by activating in turn all the associated
hidden configuration options, without having to specifically select
any wireless module(s).

This reverts commit c2f96db0.
(rejected upstream commit url https://lkml.org/lkml/2019/9/6/878

)
Bug: 140250271
Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Change-Id: I7ca31317df82cf3a349ba6cc2dc42c37090625be
Signed-off-by: Mark Salyzyn <salyzyn@google.com>