Fix W=1 warning by commenting unused SiS_TVDelay* variables.

The SiS_TVDelay* variables seem to contain some magic numbers
so looks like data worth keeping around but not as code we build.

v2:
  - Update subject (Lee)
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Cc: Lee Jones <lee.jones@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201128224114.1033617-9-sam@ravnborg.org