Remove RBC_BOARD_CONFIG

Always enable the rbc board config along with
the product config now that board config works
well.

Bug: 231224938
Test: Presubmits
Change-Id: I52a79d53dfe54878477ee015bd21863c4cee6b05
diff --git a/core/board_config.mk b/core/board_config.mk
index dc50a68..8074225 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -234,10 +234,7 @@
   .KATI_READONLY := TARGET_DEVICE_DIR
 endif
 
-# TODO(colefaust) change this if to RBC_PRODUCT_CONFIG when
-# the board configuration is known to work on everything
-# the product config works on.
-ifndef RBC_BOARD_CONFIG
+ifndef RBC_PRODUCT_CONFIG
 include $(board_config_mk)
 else
   $(shell mkdir -p $(OUT_DIR)/rbc)