Include the Pixel common board configuration

In particular, the config builds the hashtree with SHA256 for verified boot
2.0.

Bug: 156162446
Test: build an image, run avbtool info_image
Change-Id: Ib588472434f5df0265d8b457c184272ae4b566fb
diff --git a/BoardConfig-common.mk b/BoardConfig-common.mk
index 6a95618..f030248 100644
--- a/BoardConfig-common.mk
+++ b/BoardConfig-common.mk
@@ -14,6 +14,7 @@
 # limitations under the License.
 #
 include build/make/target/board/BoardConfigMainlineCommon.mk
+include build/make/target/board/BoardConfigPixelCommon.mk
 
 # Should be uncommented after fixing vndk-sp violation is fixed.
 PRODUCT_FULL_TREBLE_OVERRIDE := true