Some K100 devices identify on different product IDs. This commit
introduces support for a known optical variant.
Key points for this commit are:
- Introduction of a new product ID 0x1bc5 as P_K100_OPTICAL_VARIANT
- This variant uses the more common endpoints 0x4 and 0x84
- This variant returns 0x06 as "not supported" instead of the
anticipated 0x01.
