ath10k: fix recently introduced checkpatch warnings

Checkpatch found these issues:

drivers/net/wireless/ath/ath10k/ce.h:324: Please use a blank line after function/struct/union/enum declarations
drivers/net/wireless/ath/ath10k/core.c:1321: Please don't use multiple blank lines
drivers/net/wireless/ath/ath10k/htt.h:1859: Please use a blank line after function/struct/union/enum declarations

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>