It was never complete, even for F1 family code, and went on to be even
less complete for f0 and f3. The usefulness of a library function to
check for both the irq being enabled _and_ the status flag is highly
questionable, and caused known user confusion.
The existing, much simpler, and fully functional usart_get_flag() is
a good replacement in almost all sane use cases.
Fixes https://github.com/libopencm3/libopencm3/issues/734
to remove variations, redundancies, add missing, fix errors. All c files
refer only to the dispatch style headers in /include/stm32. Those headers
#include memorymap.h and cm3/common.h. All references to
these are removed from the family specific headers. Ethernet untouched as
it appears incomplete.
Added dummy spi.c for F0/F3. Fix some doxygen anomalies.
