Clean $OUT/ramdisk_16k dir during installclean

This dir is added during aosp/2595672 for building a 16K page sized
ramdisk.
Bug: 253827893

Change-Id: I0f4b1adff12d2b140aa73fd1b8ee1c606d917a47
diff --git a/ui/build/cleanbuild.go b/ui/build/cleanbuild.go
index ee53327..41cb5ab 100644
--- a/ui/build/cleanbuild.go
+++ b/ui/build/cleanbuild.go
@@ -135,6 +135,7 @@
 		productOut("obj/NOTICE_FILES"),
 		productOut("obj/PACKAGING"),
 		productOut("ramdisk"),
+		productOut("ramdisk_16k"),
 		productOut("debug_ramdisk"),
 		productOut("vendor_ramdisk"),
 		productOut("vendor_debug_ramdisk"),