clk: msm: clock-cpu: Add panic handler to dump cpu frequency

CPU clock frequency is required to be dumped when the device
panics, add a panic notifier to dump the cached clock frequency.

CRs-Fixed: 1050919
Change-Id: Ic5da44660f8a5356eb539113c50405ba84ace049
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>