Drop UGM per set fragment threshold to 3

BSpec: 54833
Signed-off-by: Shekhar Chauhan <shekhar.chauhan@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
[mattrope: moved above xehpsdv block for consistency]
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230922155356.583595-1-shekhar.chauhan@intel.com