drm/i915: refactor ring error state capture to use arrays

The code already got unwieldy and we want to dump more per-ring
registers.

Only functional change is that we now also capture the video
ring registers on ilk.

v2: fixup a refactor fumble spotted by Chris Wilson.

Reviewed-by: Eugeni Dodonov <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Signed-off-by: Ben Widawsky <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
4 files changed