Update SVN to 4 for SMR

Bug: 170056095
Change-Id: Ie01870216eb148e5d1d105fadb192a781143ae47
(cherry picked from commit 23c62e6f13c9b948ae4f9b6d7dec70618de96247)
diff --git a/device-common.mk b/device-common.mk
index 1d9adec..8d5fc35 100644
--- a/device-common.mk
+++ b/device-common.mk
@@ -837,7 +837,7 @@
 
 # Increment the SVN for any official public releases
 PRODUCT_PROPERTY_OVERRIDES += \
-	ro.vendor.build.svn=2
+	ro.vendor.build.svn=4
 
 # ZRAM writeback
 PRODUCT_PROPERTY_OVERRIDES += \