Add JSON metrics for i.MX8M platforms.
ChangeLogs:
V1->V2:
* remove board level metrics (bandwidth metrics).
V2->V3:
* Add the missing "ScaleUnit".
Joakim Zhang (4):
perf vendor events: Fix indentation of brackets in imx8mm metrics
perf vendor events: Add JSON metrics for imx8mn DDR Perf
perf vendor events: Add JSON metrics for imx8mq DDR Perf
perf vendor events: Add JSON metrics for imx8mp DDR Perf