Changes

Errata 2.6.10: enable watchdog on boot

Previous the code was enabling the watchdog window on boot,
but not the watchdog as the errata specified.
It seems WDT EN and WDT WEN got accidental swapped.

Use the hal defines which also describes the function
of the bits.

Change-Id: I581037724d19fb5abd0c5067f16a5769f9e264a7