drm/i915/psr: fix pipe to vblank conversion

drm/i915/psr: fix pipe to vblank conversion

First, we can't assume pipe == crtc index. If a pipe is fused off in
between, it no longer holds. intel_crtc_for_pipe() is the only proper
way to get from a pipe to the corresponding crtc.

Second, drivers aren't supposed to access or index drm->vblank[]
directly. There's drm_crtc_vblank_crtc() for this.

Use both functions to fix the pipe to vblank conversion.

Fixes: f02658c46cf7 ("drm/i915/psr: Add mechanism to notify PSR of pipe enable/disable")
Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: stable@vger.kernel.org # v6.16+
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20251106200000.1455164-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 2750f6765d6974f7e163c5d540a96c8703f6d8dd)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>