defconfig: 8910: enable watchdog in defconfig

Enable the watchdog hardware module. In case of cpu hang or deadlock
the watchdog will timeout and fire an interrupt. This will help to
capture system snapshot at the time of the crash.

Change-Id: I4fa2be6cd74d46d9922e157c409e1acfde4e9fcf
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>