drm/xe: Track pre-production workaround support

drm/xe: Track pre-production workaround support

When we're initially enabling driver support for a new platform/IP, we
usually implement all workarounds documented in the WA database in the
driver.  Many of those workarounds are restricted to early steppings
that only showed up in pre-production hardware (i.e., internal test
chips that are not available to the general public).  Since the
workarounds for early, pre-production steppings tend to be some of the
ugliest and most complicated workarounds, we generally want to eliminate
them and simplify the code once the platform has launched and our
internal usage of those pre-production parts have been phased out.

Let's add a flag to the device info that tracks which platforms still
have support for pre-production workarounds for so that we can print a
warning and taint if someone tries to load the driver on a
pre-production part for a platform without pre-production workarounds.
This will help our internal users understand the likely problems they'll
encounter if they try to load the driver on an old pre-production
device.

The Xe behavior here is similar to what we've done for many years on
i915 (see intel_detect_preproduction_hw()), except that instead of
manually coding up ranges of device steppings that we believe to be
pre-production hardware, Xe will use the hardware's own production vs
pre-production fusing status, which we can read from the FUSE2 register.
This fuse didn't exist on older Intel hardware, but should be present on
all platforms supported by the Xe driver.

Going forward, let's set the expectation that we'll start looking into
removing pre-production workarounds for a platform around the time that
platforms of the next major IP stepping are having their force_probe
requirement lifted.  This timing is just a rough guideline; there may be
cases where some instances of pre-production parts are still being
actively used in CI farms, internal device pools, etc. and we'll need to
wait a bit longer for those to be swapped out.

v2:
 - Fix inverted forcewake check

v3:
 - Invert flag and add it to the platforms on which we still have
   pre-prod workarounds.  (Jani, Lucas)

v4:
 - Avoid checking pre-production on VF since they don't have access to
   the FUSE2 register.

Bspec: 78271, 52544
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patch.msgid.link/20251212181411.294854-3-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>