Allow some Bluetooth LE related HCI request by non-root user.

[takawata]

Summary

Now Bluetooth LE related requests are not allowed by non-root user.
This patch allow request as follows:
NG_HCI_OCF_READ_LE_HOST_SUPPORTED
NG_HCI_OCF_LE_SET_SCAN_ENABLE
NG_HCI_OCF_LE_SET_SCAN_PARAMETERS
NG_HCI_OCF_LE_READ_LOCAL_SUPPORTED_FEATURES
NG_HCI_OCF_LE_READ_BUFFER_SIZE
NG_HCI_OCF_LE_READ_WHITE_LIST_SIZE

Test Plan

% hccontrol read_le_host_support
% hccontrol le_set_scan_enable enable
% hccontrol le_set_scan_enable disable
% hccontrol le_read_local_supported features
% hccontrol le_read_buffer_size
% hccontrol le_read_white_list_size

[donner]

From the netgraph part, there is no objection.