ARM: ep93xx: Disable TS-72xx watchdog before uncompressing

The TS-72xx/73xx boards have a CPLD watchdog which is configured to
reset the board after 8 seconds, if the kernel is large enough that this
takes about this time to decompress the kernel, we will encounter a
spurious reboot.

Do not pull ts72xx.h, but instead locally define what we need to disable
the watchdog.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>