ARM: at91: add pmc DT support

Specified the main Oscillator via clock binding.
This will allow to do not hardcode it anymore in the DT board at 12MHz.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/generic.h b/arch/arm/mach-at91/generic.h
index d5f5083..dd9b346 100644
--- a/arch/arm/mach-at91/generic.h
+++ b/arch/arm/mach-at91/generic.h
@@ -53,6 +53,7 @@
 extern void __init at91sam9g45_set_console_clock(int id);
 #ifdef CONFIG_AT91_PMC_UNIT
 extern int __init at91_clock_init(unsigned long main_clock);
+extern int __init at91_dt_clock_init(void);
 #else
 static int inline at91_clock_init(unsigned long main_clock) { return 0; }
 #endif