drm/i915/perf: rework mux configurations queries

Gen8+ might have mux configurations per slices/subslices. Depending on
whether slices/subslices have been fused off, only part of the
configuration needs to be applied. This change reworks the mux
configurations query mechanism to allow more than one set of registers
to be programmed.

v2: s/n_mux_regs/n_mux_configs/ (Matthew)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

drivers/gpu/drm/i915/i915_drv.h

@@ -2417,8 +2417,10 @@ struct drm_i915_private {
 
 			int metrics_set;
 
-			const struct i915_oa_reg *mux_regs;
-			int mux_regs_len;
+			const struct i915_oa_reg *mux_regs[1];
+			int mux_regs_lens[1];
+			int n_mux_configs;
+
 			const struct i915_oa_reg *b_counter_regs;
 			int b_counter_regs_len;