microblaze: Adding likely macros

On the base on GCOV analytics is helpful to add likely/unlikely
macros.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
index b108497..4d5b0311 100644
--- a/arch/microblaze/kernel/dma.c
+++ b/arch/microblaze/kernel/dma.c
@@ -37,7 +37,7 @@
 
 static unsigned long get_dma_direct_offset(struct device *dev)
 {
-	if (dev)
+	if (likely(dev))
 		return (unsigned long)dev->archdata.dma_data;
 
 	return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */