arm64: Handle 4 level page table for swapper

arm64: Handle 4 level page table for swapper

At the moment, we only support maximum of 3-level page table for
swapper. With 48bit VA, 64K has only 3 levels and 4K uses section
mapping. Add support for 4-level page table for swapper, needed
by 16K pages.

Cc: Will Deacon <[email protected]>
Signed-off-by: Suzuki K. Poulose <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Tested-by: Ard Biesheuvel <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>