MIPS: boot: fix typo in 'vmlinux.lzma.its' target

Commit 92b34a97 ("MIPS: boot: add missing targets for vmlinux.*.its")
fixed constant rebuild of *.its files on every make invocation, but due
to typo ("lzmo") it made no sense for vmlinux.lzma.its.

Fixes: 92b34a97

 ("MIPS: boot: add missing targets for vmlinux.*.its")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Alexander Lobakin <alobakin@dlink.ru>
[paulburton@kernel.org: s/invokation/invocation/]
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org