RDMA/uverbs: Fix typo of sizeof argument

Since size of 'hdr' pointer and '*hdr' structure is equal on 64-bit
machines issue probably didn't cause any wrong behavior. But anyway,
fixing of typo is required.

Fixes: da0f60df ("RDMA/uverbs: Prohibit write() calls with too small buffers")
Co-developed-by: Ivanov Mikhail <ivanov.mikhail1@huawei-partners.com>
Signed-off-by: Ivanov Mikhail <ivanov.mikhail1@huawei-partners.com>
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20230905103258.1738246-1-konstantin.meskhidze@huawei.comSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/uverbs_main.c

@@ -546,7 +546,7 @@ static ssize_t verify_hdr(struct ib_uverbs_cmd_hdr *hdr,
 	if (hdr->in_words * 4 != count)
 		return -EINVAL;
 
-	if (count < method_elm->req_size + sizeof(hdr)) {
+	if (count < method_elm->req_size + sizeof(*hdr)) {
 		/*
 		 * rdma-core v18 and v19 have a bug where they send DESTROY_CQ
 		 * with a 16 byte write instead of 24. Old kernels didn't