arm64: head: populate kernel page tables with MMU and caches on

arm64: head: populate kernel page tables with MMU and caches on

Now that we can access the entire kernel image via the ID map, we can
execute the page table population code with the MMU and caches enabled.
The only thing we need to ensure is that translations via TTBR1 remain
disabled while we are updating the page tables the second time around,
in case KASLR wants them to be randomized.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-18-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>