MIPS: tools: Build relocs tool

Build the relocs tool as part of the kbuild

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12980/
Patchwork: https://patchwork.linux-mips.org/patch/13242/
Patchwork: https://patchwork.linux-mips.org/patch/13233/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>