ARM: imx: depend MXC debug board on 3DS machines

Depend the MXC debug board on machines which actually support it.
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/Kconfig

@@ -21,6 +21,7 @@ config MXC_AVIC
 
 config MXC_DEBUG_BOARD
 	bool "Enable MXC debug board(for 3-stack)"
+	depends on MACH_MX27_3DS || MACH_MX31_3DS || MACH_MX35_3DS
 	help
 	  The debug board is an integral part of the MXC 3-stack(PDK)
 	  platforms, it can be attached or removed from the peripheral