Revert "dt-bindings: allow up to four clocks for orion-mdio"

This reverts commit 404f59e2.

This is a preparation change for merging android-4.19.61 into
msm-4.19 branch.

[1] can be reverted because it is not related to arm
and it is conflicting against [2] in msm-4.19.

[1] 404f59e2("dt-bindings: allow up to four clocks for orion-mdio")
[2] 728aba9a("Documentation: devicetree: Remove devicetree bindings from
kernel")

Change-Id: I3926c0bb50891b6ff7fdfdbbab4d02042d293306
Signed-off-by: Ivaylo Georgiev <irgeorgiev@codeaurora.org>