drm/i915/tv: Cleanup up obsolete comments

The ages old kerneldoc-esque comments still refer to the original stubs
and not the more complete functions. As they were only describing the
external entry points (or at least thought themselves to be, they had
drifted!), they don't provide any commentary for the code flow.

drivers/gpu/drm/i915/intel_tv.c:379: warning: cannot understand function prototype: 'const struct tv_mode tv_modes[] = '
drivers/gpu/drm/i915/intel_tv.c:1133: warning: bad line:
drivers/gpu/drm/i915/intel_tv.c:1140: warning: Function parameter or member 'intel_tv' not described in 'intel_tv_detect_type'
drivers/gpu/drm/i915/intel_tv.c:1140: warning: Function parameter or member 'connector' not described in 'intel_tv_detect_type'
drivers/gpu/drm/i915/intel_tv.c:1272: warning: Function parameter or member 'connector' not described in 'intel_tv_detect'
drivers/gpu/drm/i915/intel_tv.c:1272: warning: Function parameter or member 'ctx' not described in 'intel_tv_detect'
drivers/gpu/drm/i915/intel_tv.c:1272: warning: Function parameter or member 'force' not described in 'intel_tv_detect'
drivers/gpu/drm/i915/intel_tv.c:1351: warning: Function parameter or member 'connector' not described in 'intel_tv_get_modes'

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180214085814.2565-1-chris@chris-wilson.co.uk