drm/xe: select DRM_DISPLAY_DSC_HELPER

drm/xe: select DRM_DISPLAY_DSC_HELPER

The Xe driver shares display code with the i915 driver, pulling in the
dependency on the DSC helpers this way. However when working on
separating DRM_DISPLAY_DSC_HELPER this was left unnoticed. Add missing
dependency.

Fixes: ca097d4d94d8 ("drm/display: split DSC helpers from DP helpers")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409032226.x6f4SWQl-lkp@intel.com/
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240905-fix-dsc-helpers-v1-1-3ae4b5900f89@linaro.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>