MIPS: Use BUG_ON() where possible.

Based on original patch by Stoyan Gaydarov <stoyboyker@gmail.com> which
missed a few places.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/jazz/jazzdma.c b/arch/mips/jazz/jazzdma.c
index c672c08..f0fd636 100644
--- a/arch/mips/jazz/jazzdma.c
+++ b/arch/mips/jazz/jazzdma.c
@@ -68,8 +68,7 @@
 	 */
 	pgtbl = (VDMA_PGTBL_ENTRY *)__get_free_pages(GFP_KERNEL | GFP_DMA,
 						    get_order(VDMA_PGTBL_SIZE));
-	if (!pgtbl)
-		BUG();
+	BUG_ON(!pgtbl);
 	dma_cache_wback_inv((unsigned long)pgtbl, VDMA_PGTBL_SIZE);
 	pgtbl = (VDMA_PGTBL_ENTRY *)KSEG1ADDR(pgtbl);