MIPS: Kernel: Add relocate.c

MIPS: Kernel: Add relocate.c

arch/mips/kernel/relocate.c contains the functions necessary to relocate
the kernel elsewhere in memory

The kernel makes a copy of itself at the new address. It uses the
relocation table inserted by the relocs tool to fix symbol references
within the new image.

If copy/relocation is sucessful then the entry point of the new kernel
is returned, otherwise fall back to starting the kernel in place.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.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/12985/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>