wifi: iwlwifi: pcie: clean up gen1/gen2 TFD unmap

This is a bit messy right now, there are functions for both,
but then gen1 function can actually deal with both gen1 and
gen2, due to the confusion about use_tfh/gen2 cleaned up in
the previous patch.

Fix the common paths to call the right functions and remove
handling of gen2 from the gen1 function.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230816104355.baf23841ec5c.I40702e94b25db05e82f935f14548316f8c6429b9@changeid


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