drm/xe/xe2_hpg: Drop invalid workaround Wa_15010599737

drm/xe/xe2_hpg: Drop invalid workaround Wa_15010599737

Wa_15010599737 was a workaround originally proposed (and ultimately
rejected) for DG2-G10.  There's no record of it ever being relevant or
even considered for any other platforms.

The specific bit this workaround was setting is documented as "This bit
should be set to 1 for the DX9 API and 0 for all other APIs" which means
that it should almost always be left at the default value of 0 on Linux.
The register itself is directly accessible from userspace, so in the
special cases where it might be relevant (e.g., Wine/Proton running
Windows DX9 apps), the userspace drivers already have the ability to
change the setting without involvement of the kernel.

Fixes: 7f3ee7d88058 ("drm/xe/xe2hpg: Add initial GT workarounds")
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patch.msgid.link/20260223-forupstream-wa_cleanup-v3-2-7f201eb2f172@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>