ARM: at91/Kconfig: select board files automatically

An explicit selection option is not needed for board files so now we select the
board from SoC option.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[nicolas.ferre@atmel.com: remove option's comments; split patch]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/Kconfig

@@ -174,21 +174,11 @@ config SOC_AT91SAM9N12
 # ----------------------------------------------------------
 endif # SOC_SAM_V4_V5
 
-comment "Generic Board Type"
-
 config MACH_AT91RM9200_DT
-	bool "Atmel AT91RM9200 Evaluation Kits with device-tree support"
-	depends on SOC_AT91RM9200
-	help
-	  Select this if you want to experiment device-tree with
-	  an Atmel RM9200 Evaluation Kit.
+	def_bool SOC_AT91RM9200
 
 config MACH_AT91SAM9_DT
-	bool "Atmel AT91SAM Evaluation Kits with device-tree support"
-	depends on SOC_AT91SAM9
-	help
-	  Select this if you want to experiment device-tree with
-	  an Atmel Evaluation Kit.
+	def_bool SOC_AT91SAM9
 
 # ----------------------------------------------------------