drm/i915: Relocate the SKL wm sanitation code

[ Upstream commit e31e868 ]

In order to add more MBUS sanitation into the code we'll want
to reuse a bunch of the code that performs the MBUS/related
hardware programming. Currently that code comes after the
main skl_wm_get_hw_state_and_sanitize() entrypoint. In order
to avoid annoying forward declarations relocate the
skl_wm_get_hw_state_and_sanitize() and related stuff nearer to
the end of the file.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241031155646.15165-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Stable-dep-of: a97c88a ("drm/i915/wm: Verify the correct plane DDB entry")
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: vsyrjala