clk: qcom: clock-mmss-8994: Support multiple parents for byte/pixel clocks

Add additional parents for the pixel and byte clocks as these can now
switch between those. Also export the sources for the byte and pixel
clocks so that clients can switch between the parents for the relevant
RCGs.

Change-Id: If2c7fe4f12c6ad5a15f13acf71d6dc296b57b665
Signed-off-by: Pushkar Joshi <pushkarj@codeaurora.org>