wifi: iwlwifi: mvm: rs: print BAD_RATE for invalid HT/VHT index

If there's a rate->index that maps inside the range but
to an uninitialized value, then that's also a bad rate,
avoid printing "(nil)" in that case and rather print the
"BAD_RATE" string instead as in the else branch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230314194113.06b38d160fc5.I45a9254d3658b1ce796aa4c427193d3cbf638d7e@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>