RDMA/iwpm: Remove redundant initialization of pointer err_str

The pointer err_str is being initialized with a value that is never read,
it is being updated later on. The assignment is redundant and can be
removed.

Link: https://lore.kernel.org/r/20211007173942.21933-1-colin.king@canonical.com
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/iwpm_util.c

@@ -762,7 +762,7 @@ int iwpm_send_hello(u8 nl_client, int iwpm_pid, u16 abi_version)
 {
 	struct sk_buff *skb = NULL;
 	struct nlmsghdr *nlh;
-	const char *err_str = "";
+	const char *err_str;
 	int ret = -EINVAL;
 
 	skb = iwpm_create_nlmsg(RDMA_NL_IWPM_HELLO, &nlh, nl_client);