drm/i915: Move pipe enable/disable tracepoints to intel_crtc_vblank_{on,off}()

On platforms/outputs without a working frame counter we rely
on the vblank code to cook up the frame counter from the timestamps.
That requires that vblank support is enabled. Thus we need to
move the pipe enable/disable tracepoints to the other side
of the drm_vblank_{on,off}() calls. There shouldn't really be
much happening between these old and new call sites so the
tracepoints should still provide reasonable data.

The alternative would be to give up on having the frame counter
values in the trace which would render the tracepoints more or
less pointless.

v2: Missed one case in intel_ddi_post_disable()
    Drop the now useless i915_trace.h includes

Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210304170421.10901-2-ville.syrjala@linux.intel.com


Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>