At this point is sure that HSW and BDW will never have PSR enabled by
default, so here dropping it from device info and cleaning up code.

v2:
- enable psr support for display 9
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210827174253.51122-1-jose.souza@intel.com