mfd: Change tunnelcreek watchdog name on the lpc_sch subdevices array

The name of the tunnelcreek watchdog device is not tunnelcreek_wdt but
ie6xx_wdt.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>