The clock controller driver of qca8386/qca8084 is registered
as the MDIO device, the hardware register is accessed by MDIO bus
that is normally used to access general PHY device, which is
different from the current existed qcom clock controller drivers
using ioremap to access hardware clock registers, nsscc-qca8k is
accessed via an MDIO bus.

MDIO bus is commonly utilized by both qca8386/qca8084 and other
PHY devices, so the mutex lock mdio_bus->mdio_lock should be
used instead of using the mutex lock of remap.

To access the hardware clock registers of qca8386/qca8084, there
is a special MDIO frame sequence, which needs to be sent to the
device.

Enable the reference clock before resetting the clock controller,
the reference clock rate is fixed to 50MHZ.
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Luo Jie <quic_luoj@quicinc.com>
Link: https://lore.kernel.org/r/20240605124541.2711467-5-quic_luoj@quicinc.comSigned-off-by: Bjorn Andersson <andersson@kernel.org>