SkQP: remove threshold for imageblurclampmode

This fixes the failure on Mesa freedreno since Mesa commit a1c765a44c0
("freedreno/ir3: Consistently lower mediump inputs to 16-bit (when we
can).").

Bug: b/247140770
Test: cts-tradefed

Change-Id: I236f32627b250ae5eeb62cb14028a7a609f51225
1 file changed