drivers/wifi: Adapt generic wifi driver into a chip driver

drivers/wifi: Adapt generic wifi driver into a chip driver

Re-organize the existing generic wifi driver into a generic wifi chip
driver. This allows generic wifi chip information to be added to the
devicetree.

BUG=None
TEST=./util/abuild/abuild

Change-Id: I63f957a008ecf4a6a810c2a135ed62ea81a79fe0
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43768
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>