Tegra: memctrl_v1: disable AHB redirection after cold boot

During boot, USB3 and flash media (SDMMC/SATA) devices need access to
IRAM. Because these clients connect to the MC and do not have a direct
path to the IRAM, the MC implements AHB redirection during boot to allow
path to IRAM. In this mode, accesses to a programmed memory address aperture
are directed to the AHB bus, allowing access to the IRAM. The AHB aperture
is defined by the IRAM_BASE_LO and IRAM_BASE_HI registers, which are
initialized to disable this aperture. Once bootup is complete, we must
program IRAM base/top, thus disabling access to IRAM.

This patch provides functionality to disable this access. The tegra port
calls this new function before jumping to the non-secure world during
cold boot.

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