powerpc/nohash: Use IS_ENABLED() to simplify __set_pte_at()

static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,

				pte_t *ptep, pte_t pte, int percpu)

{

#if defined(CONFIG_PPC32) && defined(CONFIG_PTE_64BIT)

	/* Second case is 32-bit with 64-bit PTE.  In this case, we

	 * can just store as long as we do the two halves in the right order

	 * with a barrier in between.

	 * In the percpu case, we also fallback to the simple update

	 */

	if (percpu) {

		*ptep = pte;

		return;

	}

	if (IS_ENABLED(CONFIG_PPC32) && IS_ENABLED(CONFIG_PTE_64BIT) && !percpu) {

		__asm__ __volatile__("\

			stw%U0%X0 %2,%0\n\

			eieio\n\

			stw%U0%X0 %L2,%1"

		: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))

		: "r" (pte) : "memory");

#else

		return;

	}

	/* Anything else just stores the PTE normally. That covers all 64-bit

	 * cases, and 32-bit non-hash with 32-bit PTEs.

	 */

	*ptep = pte;

#ifdef CONFIG_PPC_BOOK3E_64

	/*

	 * With hardware tablewalk, a sync is needed to ensure that

	 * subsequent accesses see the PTE we just wrote.  Unlike userspace

	 * mappings, we can't tolerate spurious faults, so make sure

	 * the new PTE will be seen the first time.

	 */

	if (is_kernel_addr(addr))

	if (IS_ENABLED(CONFIG_PPC_BOOK3E_64) && is_kernel_addr(addr))

		mb();

#endif

#endif

}