[POWERPC] Tidy up CONFIG_PPC_MM_SLICES code

This removes some of the #ifdefs from .c files.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/mm/mmu_context_64.c b/arch/powerpc/mm/mmu_context_64.c
index 901ea76..1db38ba 100644
--- a/arch/powerpc/mm/mmu_context_64.c
+++ b/arch/powerpc/mm/mmu_context_64.c
@@ -49,18 +49,12 @@
 		return -ENOMEM;
 	}
 
-#ifdef CONFIG_PPC_MM_SLICES
 	/* The old code would re-promote on fork, we don't do that
 	 * when using slices as it could cause problem promoting slices
 	 * that have been forced down to 4K
 	 */
-	if (mm->context.id == 0)
+	if (slice_mm_new_context(mm))
 		slice_set_user_psize(mm, mmu_virtual_psize);
-#else
-	mm->context.user_psize = mmu_virtual_psize;
-	mm->context.sllp = SLB_VSID_USER |
-		mmu_psize_defs[mmu_virtual_psize].sllp;
-#endif
 	mm->context.id = index;
 
 	return 0;