MXRT600: Update to SDK 2.8.3

This release of the SDK for RT600 includes
the source code for the power management code

Signed-off-by: Mahesh Mahadevan <[email protected]>

Author: mmahadevan108

mcux/README

@@ -19,7 +19,7 @@ Status:
    LPC55S16	SDK 2.8.2 (2020-08-19)
    LPC55S69	SDK 2.8.2 (2020-08-19)
    MIMX8MM	SDK 2.8.0 (2020-07-21)
-   MIMXRT685	SDK 2.8.2 (2020-08-19)
+   MIMXRT685	SDK 2.8.3 (2020-11-09)
    MIMXRT1010	SDK 2.8.2 (2020-08-19)
    MIMXRT1015	SDK 2.8.2 (2020-08-19)
    MIMXRT1021	SDK 2.8.2 (2020-08-19)