clk: qcom: clk-rcg2: Correct the erroneous RCG configuration during enable

If the RCG frequency table does not have CXO as one of its supported
frequencies, and if a client calls clk_enable on it prior to setting
its rate, the current RCG code would configure it to the lowest
supported frequency instead which would then lead the subsequent
call to update the configuration to fail because the parent PLLs are
not active. Correct this behavior.

CRs-Fixed: 1112062
Change-Id: Ib2c09f9f503724bafd32b963b5b0ea84da7c4b7b
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>