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/apf27_defconfig b/configs/apf27_defconfig
index f001912..d77d2b5 100644
--- a/configs/apf27_defconfig
+++ b/configs/apf27_defconfig
@@ -40,6 +40,7 @@
 CONFIG_BOOTP_HOSTNAME=y
 CONFIG_BOOTP_SUBNETMASK=y
 CONFIG_FPGA_XILINX=y
+CONFIG_FPGA_SPARTAN3=y
 CONFIG_MXC_GPIO=y
 CONFIG_MMC_MXC=y
 CONFIG_NAND=y