Don't touch my host kernel. :'(

Change-Id: I33310599887ec9ae04d959752aa242b2cceb426c
wl12xx: move building of modules to target

To avoid pollution of SRC dirs, we copy the compat wifi module
sources to the target area and build it there, keeping source
area clear.

Change-Id: Id077c974f30d58851dc6e31b8d77f9dabbade5b8