zenfone9: Remove obsolete dex settings

This block is completely redundant because..
- WITH_DEXPREOPT := true is the default
- WITH_DEXPREOPT_PIC is never read
- DEX_PREOPT_DEFAULT := nostripping has no effect when the
  BOARD_USES_SYSTEM_OTHER_ODEX flag is set to true

Test: make
Change-Id: Ic9b5620bbaaf86d592edf133a5b7c44975309b4d
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 22da1ba..30cb082 100755
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -95,13 +95,6 @@
 # charger
 BOARD_CHARGER_DISABLE_INIT_BLANK := true
 
-# Dex
-ifeq ($(HOST_OS),linux)
-  ifneq ($(TARGET_BUILD_VARIANT),eng)
-    WITH_DEXPREOPT ?= true
-  endif
-endif
-
 # Display
 TARGET_SCREEN_DENSITY := 440
 SOONG_CONFIG_qtidisplay_displayconfig_enabled := true