armv8/cache: Fix page table creation

While generating the page tables, a running integer index is shifted by
SECTION_SHIFT (29) and causes overflow for any integer bigger than 7.
The page tables therefore alias to the same 8 sections and cause U-Boot
to hang once the MMU is enabled.

Fix this by making the index a 64-bit unsigned integer and so avoid the
overflow.

swarren notes: currently "i" ranges from 0..8191 on all ARM64 boards, and
"j" varies depending on RAM size; from 4 to 11 for a board with 4GB at
physical address 2GB, as some Tegra boards have.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>