Rename directories to indicate that FT930 and FT900 devices are both covered by the same SDK and src/portable code. Board makefile includes __FT900__ macro for FT90x and __FT930__ macro for boards with FT93x.

hw/mcu/bridgetek/ft9xx/Readme.md

@@ -1,6 +1,7 @@
 # BridgeTek FT9xx MCU
 
 **BridgeTek** provides a hardware abstraction library with software source code for the SDKs for FT9xx software family.
-The pre-built libraries and the source code can be redistributed.
-Registers definition files `<sdk>/include/registers/ft900_registers.h` and included peripheral register definition files have licenses that allow for redistribution.  
-Whole SDK repository is installed as part of the FT9xx Toolchain and can be downloaded from BridgeTek web page `https://www.brtchip.com`
+
+Whole SDK repository is installed as part of the FT9xx Toolchain and can be downloaded from BridgeTek web page `https://www.brtchip.com`. 
+
+Registers definition files, and included peripheral register definition files have licenses that allow for redistribution.