[AVR32] Add mach-specific Kconfig

Include at32ap-specific Kconfig file from top-level Kconfig file. The
at32ap Kconfig is currently empty, but it will grow some machine-
specific options soon.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index ce4013a..257b836 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -116,6 +116,8 @@
 	bool "U-Boot (or similar) bootloader"
 endchoice
 
+source "arch/avr32/mach-at32ap/Kconfig"
+
 config LOAD_ADDRESS
 	hex
 	default 0x10000000 if LOADER_U_BOOT=y && CPU_AT32AP7000=y