tusb: rename `foosn` to `valentyusb`
tusb: rename `foosn` to `valentyusb`

Use the name `valentyusb` as the vendor for the `valentyusb`
project, rather than the manufacturer name of the Fomu device.

This is because the `valentyusb` core can be used across multiple
vendors, much like how other cores can be used across chip vendors.

Signed-off-by: Sean Cross <d7e19930cc1f42c2d0781f4d9e6f1fe5891bf9cf@xobs.io>

hathach/tinyusb,hathach/tinyusb,hathach/tinyusb