wifi: iwlwifi: mvm: print an error instead of a warning on invalid rate

In some rare occasions, the firmware may let some frames with invalid
rates, such as CCK rates on the high band, come through.  This causes
the driver to issue a warning, but since this is a possible issue and
it's not really a bug in the driver, convert the warning into an
error.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20221102165239.3d3673c70556.I13464b11d405fd6021618b0a32404cecb7e9ac51@changeid