soc: qcom: Add snapshot of watchdog_v2 driver

This is a snapshot of watchdog_v2 driver as of msm-4.14 commit
<709e9085>. (Merge "Revert "staging, android: remove
lowmemory killer from the tree"").

Change-Id: I8baa72c73a5065ce0014a77cbdf0605e0f5d1011
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>