kconfig: Convert FPGA and FPGA_ALTERA configuration to Kconfig

This converts the following to Kconfig:
   CONFIG_FPGA
   CONFIG_FPGA_ALTERA

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>
Reviewed-by: Ley Foon Tan <ley.foon.tan@intel.com>
Reviewed-by: Dinh Nguyen <dinguyen@kernel.org>
diff --git a/configs/theadorable_debug_defconfig b/configs/theadorable_debug_defconfig
index ada88e7..4d07929 100644
--- a/configs/theadorable_debug_defconfig
+++ b/configs/theadorable_debug_defconfig
@@ -44,6 +44,7 @@
 # CONFIG_SPL_PARTITION_UUIDS is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_SPL_OF_TRANSLATE=y
+CONFIG_FPGA_ALTERA=y
 CONFIG_DM_GPIO=y
 # CONFIG_MMC is not set
 CONFIG_SPI_FLASH=y