More could probably be found, but this makes some of the basic RCC defines for
the L0 much more inline with other platforms, and much less verbose. This
helps us have more identical code for library users across different targets.
This adds MCO source selection to some targets, and removes and standardizes
the mask/shift usage for all targets. For devices that support MCO2, this
supports only MCO1. No attempt has been made to extract MCO prescaler, which
is not available on all F1 and F3.
Rename rcc_ppre1_frequency and rcc_ppre2_frequency to rcc_apb1_frequency and rcc_apb2_frequency
Also add rcc_ahb_frequency (although it is not set correctly in all cases) which will be fixed by
the rcc commits later. Also fixup the only use in the library of these variables, the USART code.
And fix the typos that resulted
Make l1 generic too
Tested with a miniblink example on the l053 discovery board.
Only register definitions at this stage, no helpers.
Register definitions from RM0367r2, hopefully the biggest
superset of L0 parts.
Signed-off-by: Karl Palsson <karlp@tweak.net.au>
