We don't distinguish between STA and AP firmwares anymore, so the
firmware version checking and quirks setting in wl12xx isn't needed
anymore.

Remove implementation of .identify_fw in wl12xx and deprecated
definitions.  Don't remove the op entirely from wlcore, because it may
be needed for more fine-grained checking later.
Signed-off-by: Luciano Coelho <coelho@ti.com>