iwlwifi: silence buffer overflow warning

Smatch (and presumably other static checkers) complain that MAX_TID_COUNT is
past the end of the array.  In the resulting discussion, Zhu Yi pointed out
that this value is not used in real life and the assignment was only there to
silence a gcc warning.

If there were a bug in the surrounding code and the value were used, the
WARN_ON(!qc) would print a warning before the crash.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>