drm/i915: Drop I915_RESET_TIMEOUT and friends

These were used to set various timeouts for the reset procedure
(deciding when the engine was dead, and even if the reset itself was not
making forward progress). No longer used.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200513074809.18194-14-chris@chris-wilson.co.uk