make_ext4fs has moved to build/target/core.mk

There's no need to add make_ext4fs to each device since it's in
build/target/core.mk since commit
720479ea7e6307648c56f61d82ac12d65f218dda

Bug: 6960586
Change-Id: If2ab1d95c0c1d13a028faeae4f00dbf5e4580bfc
1 file changed