The code that handles the early fdt mapping is hard to read and does not
create the same mapping size depending on the kernel:
- for 64-bit, 2 PMD entries are used which amounts to a 4MB mapping
- for 32-bit, 2 PGDIR entries are used which amounts to a 8MB mapping
So keep using 2 PMD entries for 64-bit and use only one PGD entry for
32-bit needed to cover 4MB. Move that into a new function called
create_fdt_early_page_table which, using the same naming as
create_kernel_page_table.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>