disable CONFIG_SLUB_DEBUG for user builds

This gerrit disables CONFIG_SLUB_DEBUG for bengal user
builds. This configs tends to badly impact performance
on user builds. Therefore, it should be disabled.

Change-Id: I09c64131492af6217d3f645f0870b0c93b981492
Reviewed-on: https://gerrit.mot.com/1913031
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Rafael Ortolan <rafones@motorola.com>
Reviewed-by: Fernanda Schmidt <fschmidt@motorola.com>
Reviewed-by: Carlos Pinho <cpinho@motorola.com>
Submit-Approved: Jira Key

arch/arm64/configs/vendor/bengal-perf_defconfig

@@ -681,3 +681,4 @@ CONFIG_CORESIGHT_HWEVENT=y
 CONFIG_CORESIGHT_DUMMY=y
 CONFIG_CORESIGHT_REMOTE_ETM=y
 CONFIG_CORESIGHT_TGU=y
+# CONFIG_SLUB_DEBUG is not set