msm: watchdog: Add support for in-kernel bark FIQ for MSM9615

MSM9615 runs in secure mode and has no TZ. Therefore, it can
handle the watchdog bark FIQ in the kernel.
The FIQ handler dumps the cpu registers from all processing modes
and finally calls panic to reboot.

Change-Id: I22b83b5d528b32fd0b43a9b4e4031ef27ef243f7
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>