PCI: tegra194: Add interconnect support in Tegra234

Add support to request DRAM bandwidth (BW) with Memory Interconnect
in Tegra234 SoC. The DRAM BW required for different modes depends on
the link speed (Gen-1/2/3/4) and width/lanes (x1/x2/x4/x8).
Currently, the DRAM frequency is always set to the maximum available
but that results in the highest power consumption.
The Memory Interconnect is a software feature which uses Interconnect
framework (ICC). It adds the capability for Memory Controller (MC)
clients to request bandwidth and therefore scale DRAM frequency
dynamically depending on the required link speed so that the DRAM
energy consumption can be optimized.

Suggested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Acked-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>