ath10k: remove unused struct ath10k::dev_type

It's unused so let's get rid of it. Compile tested only, no functional changes.

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1608574994-30706-1-git-send-email-kvalo@codeaurora.org