ARC: [mm] Prevent stray dcache lines after__sync_icache_dcach()

Flush and INVALIDATE the dcache page.

This helper is only used for writeback of CODE pages to memory. So
there's no value in keeping the dcache lines around. Infact it is risky
as a writeback on natural eviction under pressure can cause un-needed
writeback with weird issues on aliasing dcache configurations.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/mm/cache_arc700.c

@@ -610,7 +610,7 @@ void __sync_icache_dcache(unsigned long paddr, unsigned long vaddr, int len)
 
 	local_irq_save(flags);
 	__ic_line_inv_vaddr(paddr, vaddr, len);
-	__dc_line_op(paddr, vaddr, len, OP_FLUSH);
+	__dc_line_op(paddr, vaddr, len, OP_FLUSH_N_INV);
 	local_irq_restore(flags);
 }