drm/xe/reg_sr: Fix leak on xa_store failure

Free the newly allocated entry when xa_store() fails to avoid a memory
leak on the error path.

v2: use goto fail_free. (Bala)

Fixes: e5283bd ("drm/xe/reg_sr: Remove register pool")
Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/20260204172810.1486719-2-shuicheng.lin@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
(cherry picked from commit 6bc6fec)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Author: ShuichengLin

drivers/gpu/drm/xe/xe_reg_sr.c

@@ -98,10 +98,12 @@ int xe_reg_sr_add(struct xe_reg_sr *sr,
 	*pentry = *e;
 	ret = xa_err(xa_store(&sr->xa, idx, pentry, GFP_KERNEL));
 	if (ret)
-		goto fail;
+		goto fail_free;
 
 	return 0;
 
+fail_free:
+	kfree(pentry);
 fail:
 	xe_gt_err(gt,
 		  "discarding save-restore reg %04lx (clear: %08x, set: %08x, masked: %s, mcr: %s): ret=%d\n",