drm/i915: Fix fast wake AUX sync len

Fast wake should use 8 SYNC pulses for the preamble
and 10-16 SYNC pulses for the precharge. Reduce our
fast wake SYNC count to match the maximum value.
We also use the maximum precharge length for normal
AUX transactions.

Cc: stable@vger.kernel.org
Cc: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329172434.18744-1-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
(cherry picked from commit 605f7c73

)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>