drm/mm: Convert to drm_printer

Including all drivers. I thought about keeping small compat functions
to avoid having to change all drivers. But I really like the
drm_printer idea, so figured spreading it more widely is a good thing.

v2: Review from Chris:
- Natural argument order and better name for drm_mm_print.
- show_mm() macro in the selftest.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1483009764-8281-1-git-send-email-daniel.vetter@ffwll.ch