Add a platform driver for the i.MX8MM SoC describing bus topology.

Bandwidth adjustments is currently only supported on the DDRC and main
NOC. Scaling for the vpu/gpu/display NICs could be added in the future.
Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Link: https://lore.kernel.org/r/b14eef179dbd837a486619724b8033490f49db72.1586174566.git.leonard.crestez@nxp.comSigned-off-by: Georgi Djakov <georgi.djakov@linaro.org>