drm/panfrost: Consolidate reset handling

Runtime PM resume and job timeouts both call the same sequence of
functions, so consolidate them to a common function. This will make
changing the reset related code easier. The MMU also needs some
re-initialization on reset, so rework its call. In the process, we
hide the address space details within the MMU code in preparation to
support multiple address spaces.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190808222200.13176-7-robh@kernel.org