clk: qcom: dispcc: Enable HW_CTL for internally sourced RCGs

Enable the HW_CTL bit on RCGs that have internal PLL sources
in order to safely reconfigure and update the RCG in the event
that it's enabled from some other hardware signal.

Change-Id: Ib278ddf609cdfdb3e1ad27583e94219aefb2149f
Signed-off-by: David Dai <daidavid1@codeaurora.org>