wifi: rtl8xxxu: Enable 40 MHz width by default

wifi: rtl8xxxu: Enable 40 MHz width by default

40 MHz support is hidden behind the ht40_2g module parameter with
this comment:

/*
 * Some APs will negotiate HT20_40 in a noisy environment leading
 * to miserable performance. Rather than defaulting to this, only
 * enable it if explicitly requested at module load time.
 */

This parameter was added in commit 26f1fad29ad9 ("New driver:
rtl8xxxu (mac80211)"). Back then rtl8xxxu only supported RTL8723AU
and the RTL8192CU family. It's entirely possible the miserable
performance was due to mistakes in the channel switching function,
which were fixed in a previous patch.

Delete the ht40_2g module parameter. If someone still needs to
disable 40 MHz support, cfg80211 has the module parameter
cfg80211_disable_40mhz_24ghz. That works too.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/4f053103-adfd-4ead-acb3-ef69127a4bab@gmail.com