dt-bindings: clock: Add support for GCC clock ids for SDM429

Add clock id's for global clock controller, multimedia clock
controller and peripheral gpu clock drivers to support gpu
PLLs and RCGs.

Change-Id: I534ff3e4ba5e9eb17a5806e7f8a57edc1761235e
Signed-off-by: Saurabh Sahu <sausah@codeaurora.org>
Signed-off-by: Chetan C R <cchinnad@codeaurora.org>