Remove CONFIG_DIST_8X8 from cmake files

CONFIG_DIST_8X8 was removed from C source files in
https://aomedia-review.googlesource.com/c/aom/+/104468, but it was not
removed from cmake files. So config/aom_config.h still defines the
CONFIG_DIST_8X8 macro. This CL removes CONFIG_DIST_8X8 from cmake files.

Change-Id: Ifc6f017a5070ccf002089e08767a2d2776ee39bc
diff --git a/build/cmake/aom_config_defaults.cmake b/build/cmake/aom_config_defaults.cmake
index 340fb6e..e69b920 100644
--- a/build/cmake/aom_config_defaults.cmake
+++ b/build/cmake/aom_config_defaults.cmake
@@ -130,7 +130,6 @@
                    "AV1 experiment: Enable tensorflow lite library.")
 set_aom_config_var(CONFIG_SPEED_STATS 0 "AV1 experiment.")
 set_aom_config_var(CONFIG_COLLECT_RD_STATS 0 "AV1 experiment.")
-set_aom_config_var(CONFIG_DIST_8X8 0 "AV1 experiment.")
 set_aom_config_var(CONFIG_ENTROPY_STATS 0 "AV1 experiment.")
 set_aom_config_var(CONFIG_INTER_STATS_ONLY 0 "AV1 experiment.")
 set_aom_config_var(CONFIG_BITSTREAM_DEBUG 0
diff --git a/build/cmake/aom_experiment_deps.cmake b/build/cmake/aom_experiment_deps.cmake
index 2e36157..3bbeb0c 100644
--- a/build/cmake/aom_experiment_deps.cmake
+++ b/build/cmake/aom_experiment_deps.cmake
@@ -21,8 +21,4 @@
     change_config_and_warn(CONFIG_INSPECTION 1 CONFIG_ANALYZER)
   endif()
 
-  if(CONFIG_DIST_8X8 AND CONFIG_MULTITHREAD)
-    change_config_and_warn(CONFIG_DIST_8X8 0 CONFIG_MULTITHREAD)
-  endif()
-
 endmacro()