Initialize device.regs according to HID descriptor

[jerrysxie]

Currently, all handlers (input, command, report description) pull addresses directly from the HID descriptor. A better approach might be to initialize device.regs when reading the HID descriptor and then have the handlers use device.regs instead. The only catch is that we’d need to lock device.regs during this process. Right now, get_hid_descriptor takes care of the locking.

@jerrysxie Should we explore this option in a separate thread?

Originally posted by @razbhe10 in #666 (comment)