ath10k: remove unused more_frags variable

Fix the following W=1 build warning:

  drivers/net/wireless/ath/ath10k/htt_rx.c:1790:7: warning: variable ‘more_frags’ set but not used [-Wunused-but-set-variable]
   1790 |  bool more_frags;
        |       ^~~~~~~~~~

Fixes: a1166b26 ("ath10k: add CCMP PN replay protection for fragmented frames for PCIe")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210526142219.2542528-1-yangyingliang@huawei.com