arm: Remove zmx25 board and ARCH_MX25

This board has not been converted to CONFIG_DM by the deadline.
Remove it.  As this is the last ARCH_MX25 platform, remove those
references as well.

Cc: Matthias Weisser <weisserm@arcor.de>
Cc: Stefano Babic <sbabic@denx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 6fbb5c1..eaa6f16 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -24,7 +24,7 @@
 
 config WATCHDOG_TIMEOUT_MSECS
 	int "Watchdog timeout in msec"
-	default 128000 if ARCH_MX25 || ARCH_MX31 || ARCH_MX5 || ARCH_MX6
+	default 128000 if ARCH_MX31 || ARCH_MX5 || ARCH_MX6
 	default 128000 if ARCH_MX7 || ARCH_VF610
 	default 30000 if ARCH_SOCFPGA
 	default 60000