drm/i915/psr: Silence period and lfps half cycle
Add get function for silence period and lfps half cycle. Values are taken
from the tables in bspec.
Bspec: 71632
v3:
- use PORT_ALPM_CTL_SILENCE_PERIOD_MASK instead of value 255
- use PORT_ALPM_LFPS_CTL_LAST_LFPS_HALF_CYCLE_DURATION_MASK instead of
value 31
v2:
- fix some checks
- add some more comments
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328141928.1311284-4-jouni.hogander@intel.com