bthidd: Consider usage ranges when dealing with array inputs.

So far, we were always using HID_USAGE() to determine the Usage ID of a
certain HID report input item. This does not work as intended if a field
is an array and the allowed usages are specified with a usage range, as
HID_USAGE() will return 0. We need to use the field value as an index in
the usage range list in this case instead.

This makes the volume keys in a Microsoft Bluetooth Mobile Keyboard
5000 be properly recognized. The relevant part of the HID report looks
like this:

0xA1, 0x01,        // Collection (Application)
0x85, 0x07,        //   Report ID (7)
0x05, 0x0C,        //   Usage Page (Consumer)
0x19, 0x00,        //   Usage Minimum (Unassigned)
0x2A, 0xFF, 0x03,  //   Usage Maximum (0x03FF)
0x95, 0x01,        //   Report Count (1)
0x75, 0x10,        //   Report Size (16)
0x15, 0x00,        //   Logical Minimum (0)
0x27, 0xFF, 0x03, 0x00, 0x00,  //   Logical Maximum (1023)
0x81, 0x00,        //   Input (Data,Array,Abs,No Wrap,Linear,Preferred
                   //   State,No Null Position)

When a key such as "volume down" is pressed, the following data is
transferred through Interrupt In:

0x07 0xEA 0x00

Differential Revision: https://reviews.freebsd.org/D2229
Reviewed by: emax
Approved by: emax
MFC after: 1 week