To activate the csg option, the driver need to set the bit2
of PLLNCR register = SSCG_CTRL: Spread Spectrum Clock Generator
of PLLn enable.
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
HSE and LSE bypass shall support both analog and digital signals.
This patch add a way to select digital bypas case in the device tree
and set the associated bit DIGBYP in RCC_BDCR and RCC_OCEN register
during clock tree initialization.
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>