ARM: tegra: fix DEBUG_LL combined with LPAE

The DEBUG_LL UART address is mapped as an MMU section, hence, the
virtual address must be section-aligned. Sections are 1MB without LPAE
and 2MB with LPAE. Tegra's virtual address was only aligned to 1MB, and
hence the mapping was set up incorrectly with LPAE enabled, thus causing
a hang early during boot. Fix this by picking a different virtual address
that is aligned to 2MB.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>