drm/xe/bmg: Update Wa_14022085890

drm/xe/bmg: Update Wa_14022085890

Set GT min frequency to 1200Mhz once driver load is complete.

v2: Review comments (Rodrigo)
v3: Apply Wa earlier so user_req_min is not clobbered.
v4: Apply to all GTs (Lucas)

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://lore.kernel.org/r/20250612-wa-14022085890-v4-3-94ba5dcc1e30@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>