Bluetooth: MGMT: reject malformed HCI_CMD_SYNC commands

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: MGMT: reject malformed HCI_CMD_SYNC commands

In 'mgmt_hci_cmd_sync()', check whether the size of parameters passed

in 'struct mgmt_cp_hci_cmd_sync' matches the total size of the data

(i.e. 'sizeof(struct mgmt_cp_hci_cmd_sync)' plus trailing bytes).

Otherwise, large invalid 'params_len' will cause 'hci_cmd_sync_alloc()'

to do 'skb_put_data()' from an area beyond the one actually passed to

'mgmt_hci_cmd_sync()'.