iris/icl+: Report same caching domain as main surface for clear color BO.
Even though the clear color BO is bound as a read-only buffer, report the same caching domain as the main BO in use_surface() (typically IRIS_DOMAIN_RENDER_WRITE) in order to avoid ping-ponging back and forth between IRIS_DOMAIN_RENDER_WRITE and IRIS_DOMAIN_OTHER_READ, which leads to increased stall-at-pixel-scoreboard synchronization between draw calls.
Fixes a 5%-10% FPS regression in some benchmarks spotted on ICL.
Edited by Francisco Jerez