drm/i915/mtl+: Disable DP/DSC SF insertion at EOL WA

Disable the workaround inserting an SF symbol between the last DSC EOC
symbol and the subsequent BS symbol. The WA is enabled by default -
based on the register's reset value - and Bspec requires disabling it
explicitly. Bspec doesn't provide an actual WA ID for this.

Bspec: 50054, 65448, 68849

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240129175533.904590-6-imre.deak@intel.com