Pulls out duplicate calls from f0/rcc.c

This fixes an issue that karlp noted and another which was mentioned on the mailing list. Basically f0 was not using rcc_common_all and so it had duplicate code in its copy of rcc.c, but it also doesn't have the new `rcc_perhipheral_enable_clock` and `rcc_peripheral_disable_clock` calls. 

Note that this is an inspection fix, it compiles cleanly but I don't have an f0 to test it on. I did verify that the code in the f0/rcc.c was identically implemented to the code in common/rcc_common_all.c but only visually.