metag: dma: remove dead code in dma_alloc_init()

Meta has 2 levels of page table so the pmd folds into the pud which
folds into the pgd. Therefore the !pmd check in dma_alloc_init() is dead
code since it essentially checks whether:
  (init_mm->pgd + 0x770) == 0

Remove the check.
Reported-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>

arch/metag/kernel/dma.c

@@ -399,11 +399,6 @@ static int __init dma_alloc_init(void)
 		pgd = pgd_offset(&init_mm, CONSISTENT_START);
 		pud = pud_alloc(&init_mm, pgd, CONSISTENT_START);
 		pmd = pmd_alloc(&init_mm, pud, CONSISTENT_START);
-		if (!pmd) {
-			pr_err("%s: no pmd tables\n", __func__);
-			ret = -ENOMEM;
-			break;
-		}
 		WARN_ON(!pmd_none(*pmd));
 
 		pte = pte_alloc_kernel(pmd, CONSISTENT_START);