drm/i915/psr: Allow DSB usage when PSR is enabled

Now as we have correct PSR2_MAN_TRK_CTL handling in place we can allow DSB
usage also when PSR is enabled for LunarLake onwards.

v2: rebase

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250213064804.2077127-14-jouni.hogander@intel.com