drm/xe: Remove gen-based mmio offsets from hw engine init

During early generations of Intel GPUs, hardware engines would sometimes move to new MMIO offsets from one platform/generation to the next. These days engines the hardware teams put more effort into ensuring that engines stay at consistent locations; even major design changes (like the introduction of standalone media) keep the MMIO location of the engine constant.

Since all platforms supported by the Xe driver are new enough to have a single MMIO offset for each engine (and since our crystal ball says that these offsets are very unlikely to change again in the foreseeable future), we can simplify the driver's engine definitions and remove the gen-based MMIO bases.

Signed-off-by: Matt Roper matthew.d.roper@intel.com