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/amcore_defconfig b/configs/amcore_defconfig
index 6a00ea2..d68d522 100644
--- a/configs/amcore_defconfig
+++ b/configs/amcore_defconfig
@@ -12,6 +12,7 @@
 CONFIG_CMD_IMLS=y
 # CONFIG_CMD_XIMG is not set
 CONFIG_LOOPW=y
+CONFIG_MX_CYCLIC=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIMER=y