ARC: Fold boards sub-menu into platform/SoC menu

This is more natural and is now doable since the choice constructs are
gone.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arc/plat-arcfpga/Kconfig b/arch/arc/plat-arcfpga/Kconfig
index ae2c017..b41e786 100644
--- a/arch/arc/plat-arcfpga/Kconfig
+++ b/arch/arc/plat-arcfpga/Kconfig
@@ -6,13 +6,21 @@
 # published by the Free Software Foundation.
 #
 
-if ARC_PLAT_FPGA_LEGACY
+menuconfig ARC_PLAT_FPGA_LEGACY
+	bool "\"Legacy\" ARC FPGA dev Boards"
+	select ISS_SMP_EXTN if SMP
+	help
+	  Support for ARC development boards, provided by Synopsys.
+	  These are based on FPGA or ISS. e.g.
+	  - ARCAngel4
+	  - ML509
+	  - MetaWare ISS
 
-menu "FPGA Board"
+if ARC_PLAT_FPGA_LEGACY
 
 config ARC_BOARD_ANGEL4
 	bool "ARC Angel4"
-	select ISS_SMP_EXTN if SMP
+	default y
 	help
 	  ARC Angel4 FPGA Ref Platform (Xilinx Virtex Based)
 
@@ -34,8 +42,6 @@
 	  -XTL (To enable CPU start/stop/set-PC for another CPU)
 	  It doesn't provide coherent Caches and/or Atomic Ops (LLOCK/SCOND)
 
-endmenu
-
 config ARC_SERIAL_BAUD
 	int "UART Baud rate"
 	default "115200"