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/xtfpga_defconfig b/configs/xtfpga_defconfig
index 1911cda..21ad5b6 100644
--- a/configs/xtfpga_defconfig
+++ b/configs/xtfpga_defconfig
@@ -15,7 +15,7 @@
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_ASKENV=y
 CONFIG_CRC32_VERIFY=y
-CONFIG_MX_CYCLIC=y
+CONFIG_CMD_MX_CYCLIC=y
 CONFIG_CMD_SAVES=y
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_PING=y