mips: setup: fix setnocoherentio() boolean setting

Correct a typo/pasto: setnocoherentio() should set
dma_default_coherent to false, not true.

Fixes: 14ac09a6 ("MIPS: refactor the runtime coherent vs noncoherent DMA indicators")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/setup.c

@@ -803,7 +803,7 @@ early_param("coherentio", setcoherentio);
 
 static int __init setnocoherentio(char *str)
 {
-	dma_default_coherent = true;
+	dma_default_coherent = false;
 	pr_info("Software DMA cache coherency (command line)\n");
 	return 0;
 }