USB: Fix DJ Hero Turntable automatic mapping & turntable multiplier

[shockdude]

Description of Changes

This change fixes 2 bugs with DJ Hero turntable binding.

• Fixed automatic mapping of the Right Turntable's axis binds, which were originally backwards for Xbox 360 turntables.
• Fixed the Turntable Multiplier setting's functionality and increased the maximum multiplier to 512x, enabling the use of Xbox 360 turntables that output a tiny axis range (1/256 of full range). Also update the setting's description.
  • This setting still doesn't work for the SDL handler for some reason, but I didn't want to touch SDL. The multiplier works with the XInput handler, which is enough to get Xbox 360 turntables working.

Rationale behind Changes

In order to play DJ Hero, a turntable controller needs to be bound. Due to the bugs described above, the process of binding Xbox 360 turntables was way more complicated than it ought to be
Fixing these bugs makes turntable binding much simpler.

Suggested Testing Steps

• Connect an Xbox 360 turntable, or other DJ Hero turntable with XInput mappings.
• In Controller settings, enable the XInput source
  
• In USB Port 1, Bindings section, connect a DJ Hero Turntable, and set Automatic Mapping on the XInput controller representing the turntable.
  
• For Xbox 360 turntables only, switch to the Settings section, and set Turntable Multiplier to 256x.
  
• Boot DJ Hero and play!

[github-actions]

Thank you for submitting a contribution to PCSX2

As this is your first pull request, please be aware of the contributing guidelines.

Additionally, as per recent changes in GitHub Actions, your pull request will need to be approved by a maintainer before GitHub Actions can run against it. You can find more information about this change here.

Please be patient until this happens. In the meantime if you'd like to confirm the builds are passing, you have the option of opening a PR on your own fork, just make sure your fork's master branch is up to date!

[lightningterror]

@sanjay900 Can you check this?

[sanjay900]

Looks good to me
I have to assume SDL doesn't work because IIRC SDL has dead zones baked in, which would probably ignore the tiny range of the table