[AVR32] Use correct config symbol when setting cpuflags

As Robert P. J. Day pointed out, the CONFIG_CPU_AT32AP7000 symbol
wasn't used for anything. It should have been used to select the
correct -mcpu= options for CFLAGS.

-mcpu=ap7000 is the default anyway, so this patch shouldn't really
make any difference, but it's always nice to do things correctly.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

arch/avr32/Makefile

@@ -16,7 +16,7 @@ AFLAGS		+= -mrelax -mno-pic
 CFLAGS_MODULE	+= -mno-relax
 LDFLAGS_vmlinux	+= --relax
 
-cpuflags-$(CONFIG_CPU_AP7000)	+= -mcpu=ap7000
+cpuflags-$(CONFIG_CPU_AT32AP7000)	+= -mcpu=ap7000
 
 CFLAGS		+= $(cpuflags-y)
 AFLAGS		+= $(cpuflags-y)