drm/i915/dsb: Disable the GOSUB interrupt

Current DSB hardware is apparently a bit borked and likes to signal
spurious GOSUB errors. We already have most for the workarounds for
this in place, but the last part is simply not enabling the corresponding
interrupt.

While at it polish up the w/a comments with the w/a number,
and consistently take the short blurp from the w/a page.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-7-ville.syrjala@linux.intel.com