drm/i915/psr: Add intel_psr_needs_block_dc_vblank for blocking dc entry

We need to block DC6 entry in case of Panel Replay as enabling VBI doesn't
prevent it in case of Panel Replay. Panel Replay switches main link off on
DC entry. This means vblank interrupts are not fired and is a problem if
user-space is polling for vblank events. For this purpose add new function
to query need for dc entry blocking on.

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240920062340.1333777-2-jouni.hogander@intel.com