clk: qcom: gcc-kona: specify BI_TCXO as clock source 0

The clk-rcg2 enable_safe_config logic requires that the safe
BI_TCXO clock source is listed in parent_map[] with src == 0.
Modify the gcc-kona source enum so that BI_TCXO is listed first
to meet this requirement.

Without this change, gcc-kona RCGs with enable_safe_config == true
will be left in their current configuration when disabled instead
of correcting switching to the 19.2 MHz BI_TCXO source.

Change-Id: I4d943a140527f9635e0fbde962a2c86b0edea3a1
Signed-off-by: David Collins <collinsd@codeaurora.org>