drm/i915: Add missing ; to __assign_str() macros in tracepoint code

I'm working on improving the __assign_str() and __string() macros to be
more efficient, and removed some unneeded semicolons. This triggered a bug
in the build as some of the __assign_str() macros in intel_display_trace
was missing a terminating semicolon.

Link: https://lore.kernel.org/linux-trace-kernel/20240222133057.2af72a19@gandalf.local.home

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 2ceea5d8

 ("drm/i915: Print plane name in fbc tracepoints")
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>