arm64: fix L1 pindex calculation in pmap_growkernel()

Use the pmap_l1_pindex() macro which accounts for the NUL2E offset.
While here, use pmap_l2_pindex() macro further down (no change).

Prompted by pull request and commit 2e33abc, making the change for
the riscv pmap.

sys/arm64/arm64/pmap.c

@@ -2962,7 +2962,7 @@ pmap_growkernel(vm_offset_t addr)
 			    VM_ALLOC_NOFREE | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
 			if (nkpg == NULL)
 				panic("pmap_growkernel: no memory to grow kernel");
-			nkpg->pindex = kernel_vm_end >> L1_SHIFT;
+			nkpg->pindex = pmap_l1_pindex(kernel_vm_end);
 			/* See the dmb() in _pmap_alloc_l3(). */
 			dmb(ishst);
 			pmap_store(l1, VM_PAGE_TO_PTE(nkpg) | L1_TABLE);
@@ -2982,7 +2982,7 @@ pmap_growkernel(vm_offset_t addr)
 		    VM_ALLOC_NOFREE | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
 		if (nkpg == NULL)
 			panic("pmap_growkernel: no memory to grow kernel");
-		nkpg->pindex = kernel_vm_end >> L2_SHIFT;
+		nkpg->pindex = pmap_l2_pindex(kernel_vm_end);
 		/* See the dmb() in _pmap_alloc_l3(). */
 		dmb(ishst);
 		pmap_store(l2, VM_PAGE_TO_PTE(nkpg) | L2_TABLE);