wifi: iwlwifi: fix double-free bug

wifi: iwlwifi: fix double-free bug

The storage for the TLV PC register data wasn't done like all
the other storage in the drv->fw area, which is cleared at the
end of deallocation. Therefore, the freeing must also be done
differently, explicitly NULL'ing it out after the free, since
otherwise there's a nasty double-free bug here if a file fails
to load after this has been parsed, and we get another free
later (e.g. because no other file exists.) Fix that by adding
the missing NULL assignment.

Cc: stable@vger.kernel.org
Fixes: 5e31b3df86ec ("wifi: iwlwifi: dbg: print pc register data once fw dump occurred")
Reported-by: Guy Kaplan <guy.kaplan@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240123200528.675f3c24ec0d.I6ab4015cd78d82dd95471f840629972ef0331de3@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>