This fixes dEQP-EGL.functional.sharing.gles2.multithread.* tests that
are hitting: "iris: Failed to submit batchbuffer: Invalid argument"
error.
v2: clear on reset rather than clear 'on-the-fly' (Kenneth Graunke)
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5537
Fixes: e4c3d3efc7 ("iris: Defer construction of the validation (exec_object2) list")
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13464>