wifi: iwlwifi: mvm: change iwl_mvm_flush_sta() API

This API is type unsafe and needs an extra parameter to know
what kind of station was passed, so it has two, but really it
only needs two values. Just pass the values instead of doing
this type-unsafe dance, which will also make it better to use
for multi-link.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20231011130030.aeb3bf4204cd.I5b0e6d64a67455784bc8fbdaf9ceaf03699d9ce1@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>