sna/gen7: Request secure batches for Haswell vsync

Since commit 8ff8eb2b38
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Sep 9 16:23:04 2013 +0100

    sna/hsw: Scanline waits require both DERRMR and forcewake

we have been emitting LRI to enable vsync on the render ring. This
requires a privileged batch buffer, and whilst we were checking for
kernel support, we forgot to actually tell the kernel to submit the
batch with the right privileges.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71328
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/sna_display.c

@@ -3692,6 +3692,7 @@ static bool sna_emit_wait_for_scanline_hsw(struct sna *sna,
 	b[15] = 0x44050; /* DERRMR */
 	b[16] = ~0;
 
+	sna->kgem.batch_flags |= I915_EXEC_SECURE;
 	return true;
 }