drm/i915: Use increase_wm_latency() for the 16Gb DIMM w/a

drm/i915: Use increase_wm_latency() for the 16Gb DIMM w/a

Bump the latency for all watermark levels in the
16Gb+ DIMM w/a. The spec does ask us to do it only for level
0, but it seems more sane to bump all the levels. If the actual
memory access is slower then the wakeup (WM1+) should also
potentially happen earlier.

This also avoids the theoretical case that WM0 would get bumped
higher than WM1+. Not that it is likely to happen because the WM0
latency is always significantly lower than the WM1 latency.

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250919193000.17665-9-ville.syrjala@linux.intel.com