ARM: tegra: align carveout size

ARM: tegra: align carveout size

Align the size of the carveout region to 2M. This ensures that the size
can be accurately represented by an LPAE page table that uses sections.

This solves a bug (hang at boot time soon after printing the DRAM size)
that only shows up when the following two commits are merged together:
38b7f95ca432 ARM: HYP/non-sec: enable ARMV7_LPAE if HYP mode is supported
d10904f589b5 ARM: tegra: avoid using secure carveout RAM

Cc: Mark Kettenis <kettenis@openbsd.org>
Cc: Alexander Graf <agraf@suse.de>
Acked-by: Tom Warren <twarren@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>