powerpc/mm: ppc 603 doesn't need update_mmu_cache()

On powerpc 603, there is no hash table so get out of
update_mmu_cache() early.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6133e0f115d955fac4061536dab0fa7480a1c433.1565933217.git.christophe.leroy@c-s.fr

arch/powerpc/mm/book3s32/mmu.c

@@ -319,6 +319,8 @@ void hash_preload(struct mm_struct *mm, unsigned long ea)
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 		      pte_t *ptep)
 {
+	if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
+		return;
 	/*
 	 * We don't need to worry about _PAGE_PRESENT here because we are
 	 * called with either mm->page_table_lock held or ptl lock held