defconfig: enabled CONFIG_WATCHDOG_V2 for sdxpoorwills

Enable defconfig to compile watchdog timer driver to reset
the sdxpoorwills target in case of software fault.

Change-Id: Iee6d21b3aedd7587e96bef98a839662781c24c9c
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>