Updated the documentation so that it appears in all families
Also added it to the L1 area, but is untested. An addition to the memorymap
allows commonality and a #ifdef added to the spi_common_all code to
exclude the case of SPI3 for L1 and F0 as SPI3 doesn't exist in those.
An rcc dispatch header was added to remove same code from the spi header.
In the header:
- Fix DMA_SxCR_CT: change shift from 18 to 19
For use with the convenience functions:
- Added DMA_SxCR_CHSEL generic values
- Added DMA_STREAM - generic values
- Added dma_if_offset - rather than separating out LISR and HISR
- Added masks
- Added dma_disable_double_buffer_mode()
