ath10k: coredump: use struct_size() helper

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace code of the following form:

sizeof(*ce_hdr) + CE_COUNT * sizeof(ce_hdr->entries[0])

with:

struct_size(ce_hdr, entries, CE_COUNT)

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath10k/coredump.c

@@ -1192,8 +1192,8 @@ static struct ath10k_dump_file_data *ath10k_coredump_build(struct ath10k *ar)
 	if (test_bit(ATH10K_FW_CRASH_DUMP_CE_DATA, &ath10k_coredump_mask)) {
 		dump_tlv = (struct ath10k_tlv_dump_data *)(buf + sofar);
 		dump_tlv->type = cpu_to_le32(ATH10K_FW_CRASH_DUMP_CE_DATA);
-		dump_tlv->tlv_len = cpu_to_le32(sizeof(*ce_hdr) +
-						CE_COUNT * sizeof(ce_hdr->entries[0]));
+		dump_tlv->tlv_len = cpu_to_le32(struct_size(ce_hdr, entries,
+							    CE_COUNT));
 		ce_hdr = (struct ath10k_ce_crash_hdr *)(dump_tlv->tlv_data);
 		ce_hdr->ce_count = cpu_to_le32(CE_COUNT);
 		memset(ce_hdr->reserved, 0, sizeof(ce_hdr->reserved));