MIPS: .its targets depend on vmlinux

commit bcd7c45e0d5a82be9a64b90050f0e09d41a50758 upstream.

The .its targets require information about the kernel binary, such as
its entry point, which is extracted from the vmlinux ELF. We therefore
require that the ELF is built before the .its files are generated.
Declare this requirement in the Makefile such that make will ensure this
is always the case, otherwise in corner cases we can hit issues as the
.its is generated with an incorrect (either invalid or stale) entry
point.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: cf2a5e0b ("MIPS: Support generating Flattened Image Trees (.itb)")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16179/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>