powerpc/pgtable: Drop PTE_ATOMIC_UPDATES

40x was the last user of PTE_ATOMIC_UPDATES.

Drop everything related to PTE_ATOMIC_UPDATES.
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/dbe8438fd1ed3e500132c8ab70269d4e6cc84531.1590079968.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -259,25 +259,10 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
 				     unsigned long clr, unsigned long set, int huge)
 {
-#if defined(PTE_ATOMIC_UPDATES) && !defined(CONFIG_PTE_64BIT)
-	unsigned long old, tmp;
-
-	__asm__ __volatile__("\
-1:	lwarx	%0,0,%3\n\
-	andc	%1,%0,%4\n\
-	or	%1,%1,%5\n"
-	PPC405_ERR77(0,%3)
-"	stwcx.	%1,0,%3\n\
-	bne-	1b"
-	: "=&r" (old), "=&r" (tmp), "=m" (*p)
-	: "r" (p), "r" (clr), "r" (set), "m" (*p)
-	: "cc" );
-#else /* PTE_ATOMIC_UPDATES */
 	pte_basic_t old = pte_val(*p);
 	pte_basic_t new = (old & ~(pte_basic_t)clr) | set;
 
 	*p = __pte(new);
-#endif /* !PTE_ATOMIC_UPDATES */
 
 #ifdef CONFIG_44x
 	if ((old & _PAGE_USER) && (old & _PAGE_EXEC))