topaz: Define screen density

Change-Id: I897932511609069fcdf996c383a5329b8f731ec9
Signed-off-by: ReStranger <restranger@disroot.org>
diff --git a/BoardConfig.mk b/BoardConfig.mk
index a8f6098..6f852a8 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -11,3 +11,6 @@
 
 # Inherit the proprietary files
 include vendor/xiaomi/topaz/BoardConfigVendor.mk
+
+# Screen density
+TARGET_SCREEN_DENSITY := 440