clk: qcom: gpucc-bengal: Configure gpu_cc_gx_cxo_clk to be always-on

Add CLK_IS_CRITICAL flag for gpu_cc_gx_cxo_clk to keep it enabled
at all times. This clock is needed for GPU register access.

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

Change-Id: Ia7519d6a619fe303abd9a7d287193d484f6efcbc
Signed-off-by: Naveen Yadav <naveenky@codeaurora.org>