powerpc/8xx: Reverse order entries are written by __set_pte_at()

At the time being, with 16k pages __set_pte_at() writes table entries
in reverse order:

 294:	91 49 00 0c 	stw     r10,12(r9)
 298:	91 49 00 08 	stw     r10,8(r9)
 29c:	91 49 00 04 	stw     r10,4(r9)
 2a0:	91 49 00 00 	stw     r10,0(r9)

Allthough there should be no impact at all as it stays in a single
cacheline, reverse the writing in a more natural order.

 288:	91 49 00 0c 	stw     r10,0(r9)
 28c:	91 49 00 08 	stw     r10,4(r9)
 290:	91 49 00 04 	stw     r10,8(r9)
 294:	91 49 00 00 	stw     r10,12(r9)
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/67c3b5d44edfec054234ea9b4d05fc4b4f7f8a0e.1664346554.git.christophe.leroy@csgroup.eu

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

@@ -183,7 +183,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 	 * cases, and 32-bit non-hash with 32-bit PTEs.
 	 */
 #if defined(CONFIG_PPC_8xx) && defined(CONFIG_PPC_16K_PAGES)
-	ptep->pte = ptep->pte1 = ptep->pte2 = ptep->pte3 = pte_val(pte);
+	ptep->pte3 = ptep->pte2 = ptep->pte1 = ptep->pte = pte_val(pte);
 #else
 	*ptep = pte;
 #endif