drm/i915/perf: fix flex eu registers programming

We were reserving fewer dwords in the ring than necessary. Indeed
we're always writing all registers once, so discard the actual number
of registers given by the user and just program the whitelisted ones
once.

Fixes: 19f81df285 ("drm/i915/perf: Add OA unit support for Gen 8+")
Reported-by: Matthew Auld <matthew.william.auld@gmail.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Cc: <stable@vger.kernel.org> # v4.12+
Link: https://patchwork.freedesktop.org/patch/msgid/20170803165812.2373-6-lionel.g.landwerlin@intel.com

drivers/gpu/drm/i915/i915_perf.c

@@ -1601,11 +1601,11 @@ static int gen8_emit_oa_config(struct drm_i915_gem_request *req)
 	u32 *cs;
 	int i;
 
-	cs = intel_ring_begin(req, n_flex_regs * 2 + 4);
+	cs = intel_ring_begin(req, ARRAY_SIZE(flex_mmio) * 2 + 4);
 	if (IS_ERR(cs))
 		return PTR_ERR(cs);
 
-	*cs++ = MI_LOAD_REGISTER_IMM(n_flex_regs + 1);
+	*cs++ = MI_LOAD_REGISTER_IMM(ARRAY_SIZE(flex_mmio) + 1);
 
 	*cs++ = i915_mmio_reg_offset(GEN8_OACTXCONTROL);
 	*cs++ = (dev_priv->perf.oa.period_exponent << GEN8_OA_TIMER_PERIOD_SHIFT) |