build: remove unused ota tools

genext2fs, tune2fs, and e2fsck are no longer used by mkuserimg.sh.

Change-Id: If3e9e846e021de0973bde2702e60acdc9f4c57c7
diff --git a/core/Makefile b/core/Makefile
index 9d41b7d..449bfb5 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -970,9 +970,6 @@
 	  $(HOST_OUT_JAVA_LIBRARIES)/dumpkey.jar \
 	  $(HOST_OUT_JAVA_LIBRARIES)/signapk.jar \
 	  $(HOST_OUT_EXECUTABLES)/mkuserimg.sh \
-	  $(HOST_OUT_EXECUTABLES)/genext2fs \
-	  $(HOST_OUT_EXECUTABLES)/tune2fs \
-	  $(HOST_OUT_EXECUTABLES)/e2fsck \
 	  $(HOST_OUT_EXECUTABLES)/make_ext4fs
 
 .PHONY: otatools