wifi: iwlwifi: mvm: guard against invalid STA ID on removal

In the Linux kernel, the following vulnerability has been resolved: wifi: iwlwifi: mvm: guard against invalid STA ID on removal Guard against invalid station IDs in iwl_mvm_mld_rm_sta_id as that would result in out-of-bounds array accesses. This prevents issues should the driver get into a bad state during error handling.