avr32: Rename pm_init() as clk_init() and make SoC-specific

pm_init() was always more about clock initialization than anything
else. Dealing with PLLs, clock gating and such is also inherently
SoC-specific, so move it into a SoC-specific directory.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

include/asm-avr32/arch-at32ap700x/clk.h

@@ -75,6 +75,8 @@ static inline unsigned long get_mci_clk_rate(void)
 }
 #endif
 
+extern void clk_init(void);
+
 /* Board code may need the SDRAM base clock as a compile-time constant */
 #define SDRAMC_BUS_HZ	(MAIN_CLK_RATE >> CFG_CLKDIV_HSB)