net: hns3: add validity check for message data length

Add validity check for message data length in function
hclge_send_mbx_msg(), avoid unexpected overflow.

Fixes: dde1a86e ("net: hns3: Add mailbox support to PF driver")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>