wifi: iwlwifi: Fix uninitialized variable with __free()

wifi: iwlwifi: Fix uninitialized variable with __free()

Pointers declared with the __free(kfree) attribute need to be initialized
because they will be passed to kfree() on every return path.  There are
two return statement before the "cmd" pointer is initialized so this
leads to an uninitialized variable bug.

Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/f7c17a7f-f173-43bf-bc39-316b8adde349@stanley.mountain
Signed-off-by: Johannes Berg <johannes.berg@intel.com>