Convert CONFIG_CMD_FPGAD to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_FPGAD

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/iocon_defconfig b/configs/iocon_defconfig
index 2529181..eeeb933 100644
--- a/configs/iocon_defconfig
+++ b/configs/iocon_defconfig
@@ -17,6 +17,7 @@
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
 CONFIG_LOOPW=y
+CONFIG_CMD_FPGAD=y
 CONFIG_CMD_DHCP=y
 # CONFIG_CMD_NFS is not set
 CONFIG_CMD_MII=y