drm/i915/psr: Improve fast and IO wake lines calculation

drm/i915/psr: Improve fast and IO wake lines calculation

Current fast and IO wake lines calculation is assuming fast wake sync
length is 18 pulses. Let's improve this by checking actual length.

Add getter for IO buffer wake time and return 10 us there which was assumed
with static 42 us IO wake time. Upcoming patches will extent this for
different display versions.

Bspec: 65450

v3:
  - s/get_io_buffer_wake_time/io_buffer_wake_time/ and use it directly in
    calculation.
v2:
  - rename io_wake_time in if block to io_buffer_wake_time
  - rename get_io_wake_time to get_io_buffer_wake_time

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240313133221.868391-3-jouni.hogander@intel.com