Shorten test time of AVxFirstPassEncoderThreadTest

This commit reduces the number of cpu-used/tile_row/tile_col
combinations used in the test. The intention is to reduce the test
time but still proides good coverage of a great number of  possible
combinations.

Change-Id: Icd58a7aff9c6bebf8325333f311389d6532d0709
diff --git a/test/ethread_test.cc b/test/ethread_test.cc
index 369eaa5..674b61a 100644
--- a/test/ethread_test.cc
+++ b/test/ethread_test.cc
@@ -441,8 +441,8 @@
 // first pass stats test
 AV1_INSTANTIATE_TEST_CASE(AVxFirstPassEncoderThreadTest,
                           ::testing::Values(::libaom_test::kTwoPassGood),
-                          ::testing::Range(0, 6), ::testing::Range(0, 3),
-                          ::testing::Range(0, 3));
+                          ::testing::Range(0, 6, 2), ::testing::Range(0, 2),
+                          ::testing::Range(1, 3));
 
 // For AV1, test speed 0, 1, 2, 3, 5.
 // Only test cpu_used 2 here.