We repeatedly (and more so in future) use the same looping construct
over the mocs definition table to setup the register state. Refactor the
loop construct into a reusable macro.

add/remove: 2/1 grow/shrink: 1/2 up/down: 113/-330 (-217)
Function                                     old     new   delta
intel_mocs_init_engine.cold                    -      71     +71
offset                                         -      28     +28
__func__                                   17273   17287     +14
intel_mocs_init                              143     113     -30
mocs_register.isra                            91       -     -91
intel_mocs_init_engine                       503     294    -209
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191112223600.30993-3-chris@chris-wilson.co.uk