Convert CONFIG_MX_CYCLIC to Kconfig

This converts the following to Kconfig:
   CONFIG_MX_CYCLIC

Signed-off-by: Adam Ford <aford173@gmail.com>
Acked-by: David Lechner <david@lechnology.com>
diff --git a/configs/xtfpga_defconfig b/configs/xtfpga_defconfig
index deb9799..051bba0 100644
--- a/configs/xtfpga_defconfig
+++ b/configs/xtfpga_defconfig
@@ -13,6 +13,7 @@
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_ASKENV=y
 CONFIG_CRC32_VERIFY=y
+CONFIG_MX_CYCLIC=y
 CONFIG_CMD_SAVES=y
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_PING=y