Update Sunfish SVN to 31

Bug: 198443012
Change-Id: Iea34a53431d0ee233121128ad4b8400ff866a2ee
(cherry picked from commit 4e47f5082f0b85465528053a8d95d47ab858cb4d)
diff --git a/device.mk b/device.mk
index f449f08..28cff09 100644
--- a/device.mk
+++ b/device.mk
@@ -880,7 +880,7 @@
 
 # Increment the SVN for any official public releases
 PRODUCT_PROPERTY_OVERRIDES += \
-	ro.vendor.build.svn=30
+	ro.vendor.build.svn=31
 
 PRODUCT_COPY_FILES += \
     $(LOCAL_PATH)/powerhint.json:$(TARGET_COPY_OUT_VENDOR)/etc/powerhint.json