drm/i915/gt/uc: drop unused but set variable sseu

Prepare for re-enabling -Wunused-but-set-variable.

Apparently sseu is leftover from commit 9a92732f ("drm/i915/gt: Add
general DSS steering iterator to intel_gt_mcr").
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/d542f25bffd5a50ff621bee93415a972c7768a2a.1685119007.git.jani.nikula@intel.com

drivers/gpu/drm/i915/gt/uc/intel_guc_capture.c

@@ -301,7 +301,6 @@ guc_capture_alloc_steered_lists(struct intel_guc *guc,
 	const struct __guc_mmio_reg_descr_group *list;
 	struct __guc_mmio_reg_descr_group *extlists;
 	struct __guc_mmio_reg_descr *extarray;
-	struct sseu_dev_info *sseu;
 	bool has_xehpg_extregs;
 
 	/* steered registers currently only exist for the render-class */
@@ -318,7 +317,6 @@ guc_capture_alloc_steered_lists(struct intel_guc *guc,
 	if (has_xehpg_extregs)
 		num_steer_regs += ARRAY_SIZE(xehpg_extregs);
 
-	sseu = &gt->info.sseu;
 	for_each_ss_steering(iter, gt, slice, subslice)
 		num_tot_regs += num_steer_regs;