wireless: remove CONFIG_WIRELESS_WDS

wireless: remove CONFIG_WIRELESS_WDS

WDS has long been superseded by 4-addr AP/client and lacks such
fundamental features like encryption, capability negotiation,
and similar. As such, it was basically always unusable as is.

Back in 2016, in commit 8f20542386c5 ("wireless: deprecate WDS
and disable by default") I disabled it and made the Kconfig option
only available under CONFIG_EXPERT to turn it back on. Since then,
nobody has complained about that, and given the severe limitations
with the code, it's unlikely anyone would have a reason to.

Remove the Kconfig option now, so we can clean up the associated
code in follow-up patches.

Link: https://lore.kernel.org/r/20201109105103.7d1e44c50e21.I2c0a1705fd6491d9ba3400c88415ee2c4832ae98@changeid
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>