ARC: [plat-eznps] Use dedicated user stack top

NPS use special mapping right below TASK_SIZE.
Hence we need to lower STACK_TOP so that user stack won't
overlap NPS special mapping.

Signed-off-by: Noam Camus <noamc@ezchip.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/mm/tlb.c

@@ -819,6 +819,12 @@ void arc_mmu_init(void)
 	 */
 	BUILD_BUG_ON(!IS_ALIGNED((CONFIG_ARC_KVADDR_SIZE << 20), PMD_SIZE));
 
+	/*
+	 * stack top size sanity check,
+	 * Can't be done in processor.h due to header include depenedencies
+	 */
+	BUILD_BUG_ON(!IS_ALIGNED(STACK_TOP, PMD_SIZE));
+
 	/* For efficiency sake, kernel is compile time built for a MMU ver
 	 * This must match the hardware it is running on.
 	 * Linux built for MMU V2, if run on MMU V1 will break down because V1