dt-bindings: marvell,pxa168: add clock ids for SDH AXI clocks

These are clocks shared by SDH0/1 and SDH2/3, respectively.

Signed-off-by: Doug Brown <doug@schmorgal.com>
Link: https://lore.kernel.org/r/20220612192937.162952-12-doug@schmorgal.com


Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>