to remove errors, duplications and inconsistencies.
File lib/stm32/f1/pwr.c - all code removed as it duplicates that in common/pwr_common.c
Remaining changes do not affect code. Compiles OK.
TODO efm32 has no code so generates no modules
TODO F2 needs pwr.c
TODO L1 needs dma.h and dma.c
Clearing a single bit in DMA_CCR, then immediately writing a 0 over the
entire register is completely redundant on the F1, F3 and L1 DMA
peripherals. (Unlike the F2 & F4 DMA Peripheral, where this is
required)