sm8350-common: 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: I618a1e395ca1a14555cd50eef1a4f1aa079b553d

BoardConfigCommon.mk

@@ -63,13 +63,6 @@ BUILD_BROKEN_USES_BUILD_COPY_HEADERS := true
 # Camera
 TARGET_USES_QTI_CAMERA_DEVICE := true
 
-# Dex
-ifeq ($(HOST_OS),linux)
-  ifneq ($(TARGET_BUILD_VARIANT),eng)
-    WITH_DEXPREOPT ?= true
-  endif
-endif
-
 # Display
 TARGET_SCREEN_DENSITY := 440
 TARGET_USES_HWC2 := true