ath11k: define max_radios in hw_params

IPQ6018 needs different value for max_radios so make it configurable via hw_params.

No functional changes. Compile tested only.

Signed-off-by: Anilkumar Kolli <akolli@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1592316055-24958-4-git-send-email-kvalo@codeaurora.org