[d3d9] Expose support for D16_LOCKABLE only on AMD

[WinterSnowfall]

Tests of both modern and d3d8/d3d9 era drivers show that D16_LOCKABLE is and was only ever supported on AMD.

P.S.: Reference outputs here.

I've also taken the liberty to clean up the D32 configs and what was left of the validation logic, since we've removed support for it globally quite some time ago.