msm: watchdog: Flush caches before calling panic

After we dump the current context in the fiq bark handler,
we call panic and wait to restart into download mode without
flushing the caches. Flush the cache before calling panic to
ensure that data is written out.

Change-Id: I507ffaafa1c8206d682a49f70fae30e4d408993e
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>