arm64/mm: remove pointless map/unmap sequences when creating page tables

The routines __pud_populate and __pmd_populate only create a table
entry at their respective level which refers to the next level page
by its physical address, so there is no reason to map this page and
then unmap it immediately after.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/mmu.c

@@ -128,9 +128,7 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 		phys_addr_t pte_phys;
 		BUG_ON(!pgtable_alloc);
 		pte_phys = pgtable_alloc();
-		pte = pte_set_fixmap(pte_phys);
 		__pmd_populate(pmd, pte_phys, PMD_TYPE_TABLE);
-		pte_clear_fixmap();
 	}
 	BUG_ON(pmd_bad(*pmd));
 
@@ -168,9 +166,7 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 		phys_addr_t pmd_phys;
 		BUG_ON(!pgtable_alloc);
 		pmd_phys = pgtable_alloc();
-		pmd = pmd_set_fixmap(pmd_phys);
 		__pud_populate(pud, pmd_phys, PUD_TYPE_TABLE);
-		pmd_clear_fixmap();
 	}
 	BUG_ON(pud_bad(*pud));