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/mm/pgtable.c b/arch/microblaze/mm/pgtable.c
index 63a6fd0..d31312c 100644
--- a/arch/microblaze/mm/pgtable.c
+++ b/arch/microblaze/mm/pgtable.c
@@ -154,7 +154,7 @@
 		err = 0;
 		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
 				__pgprot(flags)));
-		if (mem_init_done)
+		if (unlikely(mem_init_done))
 			flush_HPTE(0, va, pmd_val(*pd));
 			/* flush_HPTE(0, va, pg); */
 	}