wifi: iwlwifi: mld: silence uninitialized variable warning

The "resp_len" isn't initialized if iwl_dhc_resp_data() fails.

Fixes: b611cf6b ("wifi: iwlwifi: mld: add support for DHC_TOOLS_UMAC_GET_TAS_STATUS command")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/add9c9e2-3b44-4e0a-a4aa-7326f6425baf@stanley.mountain


[fix typo in commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>