[build] add support for EFR32 devices on Thread 1.3 (#8)

Main changes:
- Add ot-efr32 to build script
- Add `ot-efr32` submodule
- Skip Silabs apps in ot-efr32
- Limit efr32 to only brd4166a.
- Refactor `./script/make-firmware.bash`
    - If no platform is specified, the script will build all platforms.
    If a platform is specified as an argument, the script will build
    only that platform

Other changes:
- Allow relative paths for OUTPUT_ROOT when running make-firmware.bash directly
- Add support for downloading nrfutil on MacOS
- Use wildcard to simplify .gitignore

.gitignore

@@ -1,2 +1,3 @@
-build
+build*/
+output/
 .idea

.gitmodules

@@ -17,3 +17,6 @@
 [submodule "openthread-1.1"]
 	path = openthread-1.1
 	url = https://github.com/openthread/openthread.git
+[submodule "ot-efr32"]
+	path = ot-efr32
+	url = https://github.com/openthread/ot-efr32

CHANGELOG.txt

@@ -13,6 +13,11 @@ FEATURES
 
 CHANGELOG
 ==========
+* 08/18/2021 (commitid:95c5cb793, main)
+    * Add efr32mg12 (brd4166a) support for Thread 1.3 builds
+
+    * Build scripts
+        * Refactor to allow new platforms to be added easily
 
 * 06/15/2021 (commitid:4b36e5115, main)
 

README.md

@@ -21,11 +21,11 @@ At the root of the repository:
 $ REFERENCE_RELEASE_TYPE=(certification|1.3)  [SD_CARD=/dev/...] [IN_CHINA=(0|1)] ./script/make-reference-release.bash
 ```
 
-This will produce a reference release folder in `./build/`. The folder will be 
+This will produce a reference release folder in `./build/`. The folder will be
 named after the release type, date and the OpenThread commit id.
 
-`SD_CARD` is expected to be the device file path of an SD card inserted to 
-the host. If this variable is specified, the script will flash the Raspberry Pi 
+`SD_CARD` is expected to be the device file path of an SD card inserted to
+the host. If this variable is specified, the script will flash the Raspberry Pi
 image containing OpenThread border router service to the SD card.
 
 If `IN_CHINA` is set to 1, the script will prefer to use apt sources based in
@@ -34,7 +34,7 @@ China so that you can save time while installing software dependencies.
 For example, if you are in China and want to flash the built image to an SD card:
 
 ```
-$ REFERENCE_RELEASE_TYPE=certification IN_CHINA=1 SD_CARD=/dev/sda ./script/make-reference-release.bash 
+$ REFERENCE_RELEASE_TYPE=certification IN_CHINA=1 SD_CARD=/dev/sda ./script/make-reference-release.bash
 ```
 
 When `REFERENCE_RELEASE_TYPE` is `certification`, reference release contains following components:
@@ -50,7 +50,9 @@ When `REFERENCE_RELEASE_TYPE` is `1.3`, reference release contains following com
 - Change log
 - Quick start guide
 
-Note: Currently, only nRF52840 dongles are supported for CLI/RCP firmwares.
+**Note**: Currently, only the following boards are supported for CLI/RCP firmwares:
+- nRF52840 dongles
+- EFR32MG12 BRD4166A boards
 
 # Contributing