ath10k: increase copy engine entries for rx wmi

Having lower number of copy engine entries for target to host
WMI ring is causing drops in receiving management frames. This
issue is observed during max clients (128 clients) stress testing.
While bursting deauthentication frames from simulated clients,
approx. 70% of frames are getting dropped due to lower ring entries.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>