ARM: at91: fix USB clock detection handling

Add more compatibles to be able to correct the USB clock detection.

at91sam9261 and at91sam9263 have the same PMC_SCSR layout as at91sam9260.
at91sam9rl doesn't have any USB clock.

Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>