Merge pull request #8794 from basilfx/feature/efm32_fix_style

boards/common/silabs/board_common.c

boards/ikea-tradfri/Makefile.dep

boards/ikea-tradfri/Makefile.features

boards/ikea-tradfri/include/board.h

boards/ikea-tradfri/include/periph_conf.h

boards/slstk3401a/board.c

boards/sltb001a/Makefile.dep

boards/sltb001a/Makefile.features

boards/sltb001a/board.c

boards/sltb001a/include/board.h

boards/sltb001a/include/periph_conf.h

boards/stk3600/Makefile.dep

boards/stk3600/Makefile.features

boards/stk3600/include/board.h

boards/stk3600/include/periph_conf.h

boards/stk3700/Makefile.dep

boards/stk3700/Makefile.features

boards/stk3700/include/board.h

boards/stk3700/include/periph_conf.h