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>
diff --git a/cpu/at32ap/at32ap700x/Makefile b/cpu/at32ap/at32ap700x/Makefile
index d276712..7404235 100644
--- a/cpu/at32ap/at32ap700x/Makefile
+++ b/cpu/at32ap/at32ap700x/Makefile
@@ -24,7 +24,7 @@
 
 LIB	:= $(obj)lib$(SOC).a
 
-COBJS	:= gpio.o
+COBJS	:= gpio.o clk.o
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))