Spidefsfix

The rest of libopenCM3 (stm32/spi.h)  depends on the definitions of SPI1_BASE and SPI2_I2S_BASE. 

The first was defined as "SPI1_I2S_BASE" in f0/memorymap.h I can find no hints that stm32F0 supports I2S, not even in SPI1. So I renamed the define to SPI1_BASE. 

The spi.h file depends on the base address for SPI2 being defined as SPI2_I2S_BASE. I've added this define although technically it is wrong because on 'F0 there is no I2S support. 

I think I might have the branching/forking/tracking/merging figured. If there is anything wrong, let me know. Doing things properly helps everybody in the long run. 

@Karlp, the "struct regaddr" was indeed from my source. /This/ is the fix to make those lines compile. :-)