wifi: rsi: Don't default to -EOPNOTSUPP in rsi_mac80211_config

[ Upstream commit d973b1039ccde6b241b438d53297edce4de45b5c ]

This triggers a WARN_ON in ieee80211_hw_conf_init and isn't the expected
behavior from the driver - other drivers default to 0 too.

Fixes: 0a44dfc07074 ("wifi: mac80211: simplify non-chanctx drivers")
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Link: https://patch.msgid.link/20260221-rsi-config-ret-v1-1-9a8f805e2f31@puri.sm
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>