fpga: Added Kconfig support for FPGA_SPARTAN3

This patch added Kconfig support for FPGA_SPARTAN3 and migrates the
values over to the defconfigs.

Signed-off-by: Vipul Kumar <vipulk@xilinx.com>
Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
diff --git a/configs/mt_ventoux_defconfig b/configs/mt_ventoux_defconfig
index 2e58ec1..97bbd8e 100644
--- a/configs/mt_ventoux_defconfig
+++ b/configs/mt_ventoux_defconfig
@@ -32,6 +32,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_BOOTP_DNS=y
 CONFIG_FPGA_XILINX=y
+CONFIG_FPGA_SPARTAN3=y
 CONFIG_SYS_OMAP24_I2C_SPEED=400000
 CONFIG_MMC_OMAP_HS=y
 CONFIG_NAND=y