Tegra: organize memory/mmio apertures to decrease memmap latency

Tegra: organize memory/mmio apertures to decrease memmap latency

This patch organizes the memory and mmio maps linearly, to make the
mmap_add_region process faster. The microsecond timer has been moved
to individual platforms instead of making it a common step, as it
further speeds up the memory map creation process.

Change-Id: I6fdaee392f7ac5d99daa182380ca9116a001f5d6
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>