All the macro arguments that are user supplied, or potentially, wrap properly
in () as good practice.
Probably missed one or two, and a lot of them are possibly unnecessary, but
it's straightforward to just do it always.
Fixes github issue #321
This adds UART support for Vybrid VF6xx. Baud rate is calculated
from IPG clock, which need to be initialized by using the
ccm_calculate_clocks functions. Also clock need to be gated using
the ccm_clock_gate_enable function. Tested with an unitialized
UART with a baud rate of 115200.
