arch: add MIPS architecture support

MIPS (Microprocessor without Interlocked Pipelined Stages) is a
instruction set architecture (ISA) developed by MIPS Computer
Systems, now MIPS Technologies.

This commit provides MIPS architecture support to Zephyr. It is
compatible with the MIPS32 Release 1 specification.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
34 files changed