wifi: rtw89: mcc: prevent shift wrapping in rtw89_core_mlsr_switch()

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtw89: mcc: prevent shift wrapping in rtw89_core_mlsr_switch()

The "link_id" value comes from the user via debugfs. If it's larger than BITS_PER_LONG then that would result in shift wrapping and potentially an out of bounds access later. In fact, we can limit it to IEEE80211_MLD_MAX_NUM_LINKS (15).

Fortunately, only root can write to debugfs files so the security impact is minimal.