Drivers: hv: kvp: check kzalloc return value

kzalloc() return value check was accidentally lost in 11bc3a5fa91f:
"Drivers: hv: kvp: convert to hv_utils_transport" commit.

We don't need to reset kvp_transaction.state here as we have the
kvp_timeout_func() timeout function and in case we're in OOM situation
it is preferable to wait.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_kvp.c

@@ -353,6 +353,9 @@ kvp_send_key(struct work_struct *dummy)
 		return;
 
 	message = kzalloc(sizeof(*message), GFP_KERNEL);
+	if (!message)
+		return;
+
 	message->kvp_hdr.operation = operation;
 	message->kvp_hdr.pool = pool;
 	in_msg = kvp_transaction.kvp_msg;