wifi: ieee80211: fix definition of EHT-MCS 15 in MRU

wifi: ieee80211: fix definition of EHT-MCS 15 in MRU

According to the definition in IEEE Std 802.11be-2024, Table 9-417r, each
bit indicates support for the transmission and reception of EHT-MCS 15 in:
- B0: 52+26-tone and 106+26-tone MRUs.
- B1: a 484+242-tone MRU if 80 MHz is supported.
- B2: a 996+484-tone MRU and a 996+484+242-tone MRU if 160 MHz is
      supported.
- B3: a 3×996-tone MRU if 320 MHz is supported.

Fixes: 6239da18d2f9 ("wifi: mac80211: adjust EHT capa when lowering bandwidth")
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Link: https://patch.msgid.link/20260313062150.3165433-1-shayne.chen@mediatek.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>