tile: use pmd_pfn() instead of casting via pte_t

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/mm/pgtable.c

@@ -127,8 +127,7 @@ void shatter_huge_page(unsigned long addr)
 	}
 
 	/* Shatter the huge page into the preallocated L2 page table. */
-	pmd_populate_kernel(&init_mm, pmd,
-			    get_prealloc_pte(pte_pfn(*(pte_t *)pmd)));
+	pmd_populate_kernel(&init_mm, pmd, get_prealloc_pte(pmd_pfn(*pmd)));
 
 #ifdef __PAGETABLE_PMD_FOLDED
 	/* Walk every pgd on the system and update the pmd there. */