drm/i915/display: Move psr related module parameters under display

Move psr related module parameters under display. Also fix error in
enable_psr2_sel_fetch module parameter descrtiption. It was saying disabled
by default while it's vice versa. Also psr_safest_params was missing
default value in description. This is now added.

v2:
  - Fix enable_psr2_sel_fetch description.
  - Add default value into psr_safest_params description.

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231024124109.384973-5-jouni.hogander@intel.com