configs: disable BUILD_TAG in default defconfig

This doesn't work in shallow checkouts and doesn't provide much value.

Change-Id: Ib7dbd8b43111784d84e5fd6ab0bc5ed53c667fdb
(cherry picked from commit 6bdf59b678c78880b5612ed266f484ab13aa281c)
diff --git a/configs/default_defconfig b/configs/default_defconfig
index 4dd4ab9..96ea66d 100644
--- a/configs/default_defconfig
+++ b/configs/default_defconfig
@@ -112,12 +112,6 @@
 	endif
 endif
 
-ifneq ($(DEVELOPER_DISABLE_BUILD_TIMESTAMP), y)
-ifneq ($(WLAN_DISABLE_BUILD_TAG), y)
-CONFIG_BUILD_TAG := y
-endif
-endif
-
 ifeq ($(CONFIG_ARCH_MDM9630), y)
 CONFIG_MOBILE_ROUTER := y
 endif