target-mips: Add M14K and M14Kc MIPS32r2 microMIPS processors

target-mips: Add M14K and M14Kc MIPS32r2 microMIPS processors

Add the M14K and M14Kc processors from MIPS Technologies that are the
original implementation of the microMIPS ISA.  They are dual instruction
set processors, implementing both the microMIPS and the standard MIPSr32
ISA.

These processors correspond to the M4K and 4KEc CPUs respectively,
except with support for the microMIPS instruction set added, support for
the MCU ASE added and two extra interrupt lines, making a total of 8
hardware interrupts plus 2 software interrupts.  The remaining parts of
the microarchitecture, in particular the pipeline, stayed unchanged.

The presence of the microMIPS ASE is is reflected in the configuration
added.  We currently have no support for the MCU ASE, including in
particular the ACLR, ASET and IRET instructions in either encoding, and
we have no support for the extra interrupt lines, including bits in
CP0.Status and CP0.Cause registers, so these features are not marked,
making our support diverge from real hardware.

Signed-off-by: Sandra Loosemore <sandra@codesourcery.com>
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>