Tegra: memctrl_v2: platform handler for MC settings

This patch empowers the platforms to provide the settings (e.g. stream ID,
security setting, transaction overrides) required by the Memory Controller
driver. This allows the platforms to program the Memory Controller as per
their needs and makes the driver scalable.

Original-change-by: Pritesh Raithatha <praithatha@nvidia.com>

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