[PATCH] Use HID descriptor for razer devices

hid-razer currently makes some guesses which device should be used to
send control messages and the size of it.

This patch derives this information from the HID descriptors, the
Windows Drivers from Razer also do this.

The crc in the blackwidow_init packet is now calculated (copied from
openrazer GPL code).

--

This is some groundwork to support more Razer devices and features.

I don't own a Razer Black Widow keyboard and used an emulator to test
this module:

https://github.com/meeuw/razer-emulator

Any feedback on this patch is appreciated, I'd also like to ask someone
to test this with real hardware.

This patch is based on v6.1.8, please let me know if I should rebase.