drm/xe/xe2lpm: Fixup Wa_14020756599

drm/xe/xe2lpm: Fixup Wa_14020756599

This WA needs to be applied to graphics GT when the media version
is 2000. Currently, media version 2000 is always paired with
graphics version 2004 which will result in writing same register
with same bits twice. We can't add optional rule in rtp
framework and also writing same register with same bits gives
warning.

Currently, media version 2000 is always paired with graphics version
2004, so just checking the latter is sufficient.

V2(Lucas):
  - Add more detail in commit message
  - Improve code comment to follow guideline

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2016
Fixes: 131328aa5699 ("drm/xe/xe2lpm: Add permanent Wa_14020756599")
Signed-off-by: Tejas Upadhyay <[email protected]>
Reviewed-by: Lucas De Marchi <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Lucas De Marchi <[email protected]>