drm/xe/guc: Don't support older GuC 70.x releases

drm/xe/guc: Don't support older GuC 70.x releases

Supporting older GuC versions comes with baggage, both on the coding
side (due to interfaces only being available from a certain version
onwards) and on the testing side (due to having to make sure the driver
works as expected with older GuCs).
Since all of our Xe platform are still under force probe, we haven't
committed to support any specific GuC version and we therefore don't
need to support the older once, which means that we can force a bottom
limit to what GuC we accept. This allows us to remove any conditional
statements based on older GuC versions and also to approach newer
additions knowing that we'll never attempt to load something older
than our minimum requirement.

As an initial value, the minimum expected version is set to 70.19,
which is the version currently in the firmware table, but the
expectation is that this will be bumbed every time we update the
table, until we remove the force probe.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240304162616.824884-1-daniele.ceraolospurio@intel.com