This is needed to switch the SCLK_HF source clock safely.
Note: these functions work on cc26x2_cc13x2 and cc26x0, but special care
needs to be taken when calling on cc26x0 some of these functions, as
ADDI_SEM needs to be taken.
Signed-off-by: Jean Pierre Dudey <jeandudey@hotmail.com>
