dt-bindings: clock: Add support for external MCLKs for LPASS on SC7280

Support external mclk to interface external MI2S clocks for SC7280.

Fixes: 4185b27b ("dt-bindings: clock: Add YAML schemas for LPASS clocks on SC7280")
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Taniya Das <quic_tdas@quicinc.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/1662005846-4838-5-git-send-email-quic_c_skakit@quicinc.com