ARM: at91: prepare at91sam9rl DT transition

Add the new names, coming from DT, for the clock lookups.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Boris BREZILLON <b.brezillon.dev@gmail.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>