ck_usbo_48m is generated by usbphyc PLL and used by OTG controller for Full-Speed use cases with dedicated Full-Speed transceiver. ck_usbo_48m is available as soon as the PLL is enabled. Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com> Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>