drm/msm: fix power handle APIs when clk are not present

Power handle API stores the clocks dt parsing return
code in to an "unsigned integer" while of_node API
may return an error code if clocks are not present
in dtsi. That may lead to invalid memory allocation
also. This patch fixes the clock parsing and avoids
free if clocks are not allocated.

Change-Id: I3199c86cfee9a3e0a97b902651841a9d2772359a
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>