clk: qcom: Mark gpu_cc_ahb_clk as critical for SM6150

Add the CLK_IS_CRITICAL flag for gpu_cc_ahb_clk to keep it
enabled at all times.  This is needed to avoid unclocked
register accesses by SMMU since SMMU vote registers do not
enable gpu_cc_ahb_clk.

Also skip an enable check for this clock since it will not
be physically enabled until gpu_cx_gdsc is enabled.

Change-Id: I83c81a20f306752a87ee0bb70ee7b1efbce5e001
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>