mac80211: twt: don't use potentially unaligned pointer

Since we're pointing into a frame, the pointer to the
twt_agrt->req_type struct member is potentially not
aligned properly. Open-code le16p_replace_bits() to
avoid passing an unaligned pointer.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: f5a4c24e ("mac80211: introduce individual TWT support in AP mode")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20210927115124.e1208694f37b.Ie3de9bcc5dde5a79e3ac81f3185beafe4d214e57@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/s1g.c

@@ -104,9 +104,11 @@ ieee80211_s1g_rx_twt_setup(struct ieee80211_sub_if_data *sdata,
 
 	/* broadcast TWT not supported yet */
 	if (twt->control & IEEE80211_TWT_CONTROL_NEG_TYPE_BROADCAST) {
-		le16p_replace_bits(&twt_agrt->req_type,
-				   TWT_SETUP_CMD_REJECT,
-				   IEEE80211_TWT_REQTYPE_SETUP_CMD);
+		twt_agrt->req_type &=
+			~cpu_to_le16(IEEE80211_TWT_REQTYPE_SETUP_CMD);
+		twt_agrt->req_type |=
+			le16_encode_bits(TWT_SETUP_CMD_REJECT,
+					 IEEE80211_TWT_REQTYPE_SETUP_CMD);
 		goto out;
 	}