drm/i915/icl: Ringbuffer interrupt handling

drm/i915/icl: Ringbuffer interrupt handling

On Gen11 interrupt masks need to be clear to allow C6 entry.
We keep them all enabled knowing that we generate extra
interrupts.

v2: Rebase.
v3: Remove gen 11 extra check in logical_render_ring_init.
v4: Rebase fixes.
v5: Rebase/refactor.
v6: Rebase.
v7: Rebase.
v8: Update comment and commit message (Daniele)

Signed-off-by: Tvrtko Ursulin <[email protected]>
Signed-off-by: Rodrigo Vivi <[email protected]>
Cc: Daniele Ceraolo Spurio <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
Signed-off-by: Mika Kuoppala <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]