ath10k: increase duty cycle maximum limit

Allow user to configure the duty cycle upto 100%. Since thermal
mitigation algorithm is running in user space, remove the driver
level limitation and let the user to control the temperature.

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