clk: qcom: gcc-ipq6018: add QUP6 I2C clock

clk: qcom: gcc-ipq6018: add QUP6 I2C clock

QUP6 I2C clock is listed in the dt bindings but it was never included in
the GCC driver.
So lets add support for it, it is marked as criticial as it is used by RPM
to communicate to the external PMIC over I2C so this clock must not be
disabled.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20231021115545.229060-1-robimarko@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>