ath10k: brace style fixes

drivers/net/wireless/ath/ath10k/htt_tx.c:457: braces {} are not necessary for single statement blocks
drivers/net/wireless/ath/ath10k/htt_tx.c:545: braces {} are not necessary for single statement blocks
drivers/net/wireless/ath/ath10k/mac.c:200: braces {} are not necessary for single statement blocks

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>