To migrate libwifi-hal module from make to soong, WIFI_ make variables
are added to soong config variables in `wifi` namespace.
Bug: 239984067
Test: m libwifi-hal
Merged-In: If60f5909619af887be8e0086a8dfef65dc97cce0
Change-Id: If60f5909619af887be8e0086a8dfef65dc97cce0
(cherry picked from commit 4abb3d43b4baf74cf7b17fee380d5b4c77a2bc9d)