ath10k: use proper service bitmap size

On 32bit systems the bitmap was too small and it
was overwritten partially by the stat completion
structure. This was visible with 10.2 firmware
only due to it using a few of the last service
ids.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>