clk: qcom: smd-rpm: Make BI_TCXO_AO critical

We should never let go of the active-only XO vote, as otherwise the
RPM may decide that there are no online users and it can be shut down,
resulting in a total, uncontrolled system collapse.

Guarantee this through adding the CLK_IS_CRITICAL flag.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Tested-by: Matti Lehtimäki <matti.lehtimaki@gmail.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230501-topic-rpmcc_xo_a-v1-3-93f18e47b607@linaro.org