cmd: mdc/mwc: normalize disjoint MX_CYCLIC usage

Both CMD_MX_CYCLIC and MX_CYCLIC are in use and defined in Kconfig,
but only the non-CMD version currently does anything. This changes all
usages to prefer the CMD_MX_CYCLIC option (since it's only affecting
addition of the commands), and switches defconfigs using the non-CMD
version to use the CMD version.

Signed-off-by: Joel Johnson <mrjoel@lixil.net>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/x600_defconfig b/configs/x600_defconfig
index bbe3923..bc106f0 100644
--- a/configs/x600_defconfig
+++ b/configs/x600_defconfig
@@ -27,7 +27,7 @@
 CONFIG_AUTOBOOT_STOP_STR=" "
 CONFIG_CMD_IMLS=y
 CONFIG_LOOPW=y
-CONFIG_MX_CYCLIC=y
+CONFIG_CMD_MX_CYCLIC=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_NAND=y