Gecko SDK v5.1.2

Corrected link to CMSIS folder

Version 4.4.0 of the Gecko SDK

Version 4.3.0 of the Gecko SDK

Version 4.2.1 of the Gecko SDK. Documentation is now hosted in the Ge…

…cko_SDK_Doc repository.

Version 4.2.0 of the Gecko SDK

Version 4.1.0 of the Gecko SDK

Initial commit of Gecko SDK. Version 4.0.0