drm/i915/tracepoints: Adjust i915_gem_ring_dispatch

Rename it to i915_gem_request_queue and fix the logged info
equivalent to the i915_gem_request even class. Also moved it
a bit further apart from the i915_gem_request_add tracepoint
since they otherwise provide similar information too close in
time.

v2: Remove sw fence singalling. We will rely on the soon to
    come GuC scheduling backend to enable that. (Chris Wilson)

v3: Log hex with 0x prefix for clarity.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>