UBUNTU: SAUCE: drm/i915: Disable PSR by default on all platforms

UBUNTU: SAUCE: drm/i915: Disable PSR by default on all platforms

BugLink: https://bugs.launchpad.net/bugs/1849947
On all Dell laptops with screens and chipsets that support PSR, both
PSR1 and PSR2 cause flickering and graphical glitches. Many laptops
don't support PSR so it isn't known if PSR works correctly on any
consumer hardware. PSR was enabled by default in 5.0 for capable
hardware, so this patch just restores the previous functionality of PSR
being disabled by default.

More info is available on the freedesktop bug:
https://gitlab.freedesktop.org/drm/intel/issues/425

Signed-off-by: Sultan Alsawaf <sultan.alsawaf@canonical.com>
Acked-by: Andrea Righi <andrea.righi@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>