Merge pull request #7500 from OTAkeys/pr/stmclk_f0_f1

boards/nucleo-f030/include/periph_conf.h

boards/nucleo-f070/include/periph_conf.h

boards/nucleo-f072/include/periph_conf.h

boards/nucleo-f091/include/periph_conf.h

boards/nucleo-f103/include/periph_conf.h

boards/nucleo-f302/include/periph_conf.h

boards/nucleo-f303/include/periph_conf.h

boards/nucleo-f334/include/periph_conf.h

boards/nucleo144-f303/include/periph_conf.h

boards/nucleo32-f031/include/periph_conf.h

boards/nucleo32-f042/include/periph_conf.h

boards/nucleo32-f303/include/periph_conf.h

boards/stm32f0discovery/include/periph_conf.h

boards/stm32f3discovery/include/periph_conf.h

cpu/stm32_common/dist/clk_conf/clk_conf.c

cpu/stm32_common/dist/clk_conf/clk_conf.h

cpu/stm32_common/doc.txt

cpu/stm32_common/stmclk.c

cpu/stm32f0/cpu.c

cpu/stm32f1/stmclk.c