wifi: iwlegacy: Remove the unused variable len

Variable len is not effectively used, so delete it.

drivers/net/wireless/intel/iwlegacy/4965-mac.c:4234:7: warning: variable 'len' set but not used.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7223


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231110073602.16846-1-jiapeng.chong@linux.alibaba.com