drm/i915/gvt: fix memory leak of a cmd_entry struct on error exit path

The error exit path when a duplicate is found does not kfree and cmd_entry
struct and hence there is a small memory leak.  Fix this by kfree'ing it.

Detected by CoverityScan, CID#1370198 ("Resource Leak")

Fixes: be1da7070a ("drm/i915/gvt: vGPU command scanner")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/cmd_parser.c

@@ -2863,6 +2863,7 @@ static int init_cmd_table(struct intel_gvt *gvt)
 		if (info) {
 			gvt_err("%s %s duplicated\n", e->info->name,
 					info->name);
+			kfree(e);
 			return -EEXIST;
 		}