Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Atmel/ATSAM3A8C/PMC/PMC_SCSR#0x0
System Clock Status Register
USB OTG Clock (48 MHz, USB_48M) Clock Status
Programmable Clock 0 Output Status
Programmable Clock 1 Output Status
Programmable Clock 2 Output Status
https://github.com/cmsis-svd/cmsis-svd-data