drm/i915: Include timeline seqno in error capture

The seqno value actually written out to memory is no longer in the
regular HWSP. Instead, it is now in its own private timeline buffer.
Thus, it is no longer visible in an error capture. So, explicitly read
the value and include that in the capture.

v2: %d -> %u (Alan)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230311063714.570389-4-John.C.Harrison@Intel.com