STM32: ADC peripheral style 1 header unification

This pulls out all the common header definitions for the F1, L1, F4 and F37x
parts.  It's verified against the datasheet for F2 as well, but we don't have
any good F2 test boards or any support for that yet.  (The F2 header would be
_exactly_ the same as the F4 header, so it's a target for a future round of
unification, not this one)

Tested with f1, f4 and l1 examples from the examples repository.
stm32: unify bulk of adc convenience functions

This unifies stm32f1, l1, and f4 convenience functions for adc.  The code
should be useable for f2 and f37x as well, but that needs hardware for testing,
and there was no existing implementation. This is the reason for the
"adc_common_v1.c" name, as trying to put all the different families into the
common file name has become too cumbersome.

All of the deprecated routines have been dropped, they've been marked
deprecated for a very long time now, and porting them seemed unnecessary.

This has been tested on f1, l1 and f4 discovery boards, and is based on some
existing l1/f1 unification code from
https://github.com/karlp/libopencm3/tree/rme_l1_master